home Endocrinology Main risk factors for malignant tumors and prevention. Tumors. General characteristics. Risk factors for the tumor process Risk factors for the tumor process

Main risk factors for malignant tumors and prevention. Tumors. General characteristics. Risk factors for the tumor process Risk factors for the tumor process

V. V. STARINSKY,
Doctor of Medical Sciences

In conditions of environmental disasters, poor diet, and constant stressful situations, the body's adaptive mechanisms are constantly working at the limit of their capabilities. The consequence of this is a sharply increased likelihood of developing diseases that lead to loss of ability to work and shorten life.

That is why one of the tasks of modern medical science is the ability to recognize changes that occur in the body and precede such diseases. Malignant neoplasms require special attention, since, unfortunately, the incidence of cancer is increasing from year to year.

The process of transforming a normal healthy cell into a tumor cell is multi-stage. The cell itself and the body as a whole undergo many changes along this path. And for a cell to degenerate into a malignant one, capable of unlimited growth, a combination of various unfavorable conditions, so-called risk factors, is necessary, each of which increases the likelihood of an oncological process. As they say, you need to know your enemies by sight.

Cancer is an age-related disease. After 40 years, the risk of developing malignant neoplasms increases significantly. The likelihood of getting sick at 70 years of age is 100 times higher than at 30 years of age. In women, however, this difference is less pronounced, since tumors of purely female localization can also occur in women. And yet, the age-related characteristics of cancer oblige every person, especially those who have crossed the 40-year mark, to consult an oncologist once a year during medical examinations or preventive examinations.

Another group of unfavorable conditions is the so-called household hazards. A certain danger to our health is posed by the high concentration of heavy metal salts and chemical compounds (nitrates, nitrites) in food products. Strict control is necessary to eliminate the possibility of accumulation of these substances in the body. In many ways, primary prevention of tumors depends on the person himself. For example, a high-fat diet increases the risk of colon, breast and prostate cancer. Abuse of smoked and pickled foods increases the likelihood of stomach cancer. There is evidence indicating a direct relationship between a lack of vitamin A in the body and lung cancer.

E. N. SOTNIKOVA,
Doctor of Medical Sciences

Smoking, alcoholism, and drug addiction have become the problem of the century. Nicotine is one of the risk factors for developing cancer of the lung, oral cavity, larynx, esophagus, bladder, pancreas, and kidneys.

To prevent the tumor process, we advise you to eat as many cruciferous vegetables as possible (cabbage, lettuce), coarse-fiber foods (whole bread, bran), and include in your diet foods rich in vitamins A and C (animal fats, carrots and other vegetables) . But do not overindulge in fatty foods - do not eat more than 15 grams of butter per day - avoid salty and smoked foods. Try to quit smoking, give up alcoholic beverages.

And one more very important commandment - avoid exposure to sunlight. Ultraviolet rays can cause irreversible changes in the genetic apparatus of the cell, laying the foundation for skin cancer.

Nowadays, the concept of endocrine-dependent tumors has become firmly established in oncology. It has already been absolutely established that various disorders of hormonal regulation lead to the development of malignant tumors in the endocrine glands and organs dependent on them. Often a person himself provokes changes in the hormonal system. For example, artificial termination of the first pregnancy significantly increases the risk of breast cancer later in life.

Considering the usually asymptomatic onset of the disease, we repeat that every person should undergo a preventive examination at least once a year with an oncologist so as not to miss the so-called pre-tumor processes and initial forms of cancer.

E. N. SOTNIKOVA, Doctor of Medical Sciences

V. V. STARINSKY, Doctor of Medical Sciences

7.4. risk factors for tumor growth

Aging. Every person, either from birth or from childhood or adolescence, is a carrier of a tumor. We are talking primarily about completely benign nevi, birthmarks, and other nodules in the skin. As you age, the number of nevi may increase, and sometimes basal cell papillomas and senile skin warts appear. After 55 years, a person enters a period when the likelihood of a malignant neoplasm progressively increases every year. Most deaths from malignant tumors occur in the age range from 55 to 74 years.

Influence of geographical areas and environmental factors.

There are significant geographic differences in cancer incidence and mortality rates. For example, mortality from stomach cancer in Japan is 7-8 times higher than in the USA, and from lung cancer, on the contrary, is 2 times higher in the USA than in Japan. Skin melanomas are 6 times more common and cause death in New Zealand than in Iceland. Most modern experts believe that there is no specific racial predisposition to certain tumors. This is confirmed by long-term comparative studies of the corresponding indicators among native residents and emigrants, representatives of the same race.

The very important role of ultraviolet rays (solar radiation), which often manifests itself in carcinogenesis, will be discussed in this chapter, and the influence of occupational factors in Chapter 9. When studying risk factors for the development of cancer, much attention is paid to people’s lifestyle: the presence of bad habits, a tendency to different excesses, traditions, dietary habits and behavior. For example, exceeding body weight by 25% of the average constitutional norm is considered an important risk factor for the development of colon and genital cancer. Chronic smoking of filter cigarettes actually increases the incidence of lung cancer (77% of men with this form of cancer are smokers), as well as cancer of the larynx, pharynx, esophagus, oral cavity, pancreas and bladder. Chronic alcoholism is a powerful risk factor for malignancy in the oropharyngeal zone, larynx, esophagus, and also in the liver (often based on cirrhosis).

A stronger tumor-producing effect of the combined effects of smoking and alcoholism is known. An important risk factor for developing cervical cancer is a large number of sexual partners, especially with early onset of sexual activity. Perhaps in this case, numerous and poorly studied viral infections of the genital organs play a significant role.

Heredity. Studies show that the mortality rate from lung cancer among non-smoking immediate relatives of people who died from this disease is 4 times higher than among non-smoking relatives of people who died from other diseases. All hereditary forms of malignant neoplasms can be divided into 3 groups: hereditary malignant tumor syndromes; familial forms of neoplasia; autosomal recessive syndromes of DNA repair disorders. Let's briefly look at each group.

Group of hereditary tumor syndromes. Includes known neoplasms in which inheritance of a single mutant gene greatly increases the risk of their development. This predisposition refers to an autosomal dominant type of inheritance. The most common example is retinoblastoma (malignant neuroepithelioma of the retina) in children. The likelihood of this tumor, often bilateral, in carriers of this gene is 10,000 times higher than in ordinary children. It has been noted that such carriers have a tendency to form a second tumor, in particular osteosarcoma. Another example is hereditary adenomatous polyposis coli, which develops shortly after birth. If children with this disease survive, grow up and live to be 50 years old, then in 100% of cases they develop colon cancer. There are several signs that characterize this group of syndromes.

In each of the syndromes, the tumor process affects a specific organ and tissue localization. Thus, type 2 multiple endocrine neoplasia syndrome concerns the thyroid gland, parathyroid glands and adrenal glands. There is no predisposition to other tumors. Within this group, tumors often have a characteristic phenotype. For example, the affected tissue may contain a large number of benign nodules (colon polyposis), or in neurofibromatosis type 1 (see Chapter 8), multiple pigmented spots on the skin (cafe au lait color) may appear, as well as Lisch nodules (A. Lisch), which are pigmented hamartomas in the iris of the eye. As with other autosomal dominant diseases, there is incomplete penetrance (frequency or probability of expression of the gene) and varying expressivity (degree of development of the trait).

Familial forms of neoplasia. In essence, all common types of malignant tumors that occur sporadically are also observed as familial forms. These are carcinomas of the colon, breast, ovaries and brain tumors. Common signs of familial neoplasm are the occurrence at an early age, the appearance in at least two or even more close relatives, and the frequent formation of bilateral or multiple lesions. Family forms are characterized by neither a characteristic phenotype nor specific dynamics. For example, in contrast to malignancy in hereditary adenomatous polyposis of the colon, the familial form of cancer of this organ does not develop from a previous glandular polyp.

Autosomal recessive syndromes of impaired DNA repair (autosomal - the same as chromosomal, except for sex chromosomes, and recessive - manifested in the phenotype). We are talking about instability of the structure of DNA or chromosomes. The group of these syndromes includes xeroderma pigmentosum (pigmentation, hyperkeratosis, edema and other skin changes due to sun exposure), Fanconi anemia, characterized by bone marrow hypoplasia, low blood cell count, and many anomalies.

In general, from 5 to 10% of human malignant tumors are associated with a hereditary predisposition. The term hereditary rather than genetic should be used, since the latter concept refers to the genetic apparatus that controls not only the transmission of hereditary characteristics, but also performs broader functions.

The role of chronic proliferative changes. The basis of malignancy is metabolic, dyshormonal, and chronic inflammatory processes. Bronchogenic cancer is often preceded by focal hyperplasia, metaplasia and dysplasia of the bronchial epithelium, which occurs in smokers under the influence of carcinogenic products on the metabolism of epithelial cells. Hyperplasia, dysplasia, as well as differentiation disorders in the lining of the vaginal portion of the cervix, which are dyshormonal in nature, can also be associated with the development of cancer. Chronic stomach ulcers, cirrhosis of the liver and other inflammatory and destructive processes of a protracted nature in many cases pose the same danger.

All these processes are classified as facultative precancerous changes and are often referred to as “precancer.” Conventionally, some benign epitheliomas can also be classified as facultative precancer. For example, a growing villous adenoma of the colon is capable of malignancy in 50% of patients, and transitional cell papilloma of the bladder - in 60% of patients.

In chronic proliferative processes of a metabolic, dyshormonal or inflammatory nature, various interstitial causes, through various mechanisms, influence the genetic control of cell proliferation and differentiation.

The development of a tumor begins from the moment the body comes into contact with a carcinogen, a factor that triggers the active transformation of healthy cells into tumor cells, and continues for 10-15 years until the clinical appearance of a tumor disease. An important role in the development of a tumor is played by disturbances in the functioning of the immune system, which interfere with the performance of its most important function - the destruction of modified cells that can become a source of tumor growth. Carcinogens known today are divided into three groups: physical, chemical and biological. Physical factors include solar and ionizing radiation, X-ray and electromagnetic radiation, exposure to high or low temperatures, etc. The group of chemical carcinogens consists of petroleum products, benzene, nitrates, halogens, alcohol, tobacco smoke tar, preservatives, dyes, paints, varnishes, solvents, heavy metal salts, combustion products, and some medications. The group of biological carcinogens includes viruses, bacteria, fungi, protozoa, which increase the rate of formation of tumor cells and change the body's response to them. This far from complete list of carcinogens is regularly updated with new factors arising from technological progress, industrial development and environmental pollution.

Prevention of cancer

So, cancer prevention is a set of measures aimed at preventing the development of tumor diseases. These activities are carried out in the following areas.

Impact on human lifestyle includes quitting smoking, limiting the amount of alcohol consumed, rational nutrition, maintaining normal body weight and combating obesity, regular physical activity, competent family planning - avoiding promiscuity, rational use of contraceptives, and abandoning abortion as a method of contraception.

Nutrition. The concept of rational nutrition includes:

eating food at an optimal temperature that does not irritate or cause burns to the mucous membrane of the mouth, pharynx and esophagus;
regular 3-4 meals a day;
the correct ratio of proteins, fats, carbohydrates in the diet, sufficient fortification of food, sufficient, but not excessive caloric content of the diet;
exclusion from the diet of products containing hormones used in animal husbandry, growth accelerators, antibiotics, as well as preservatives, dyes and other potentially carcinogenic substances;
limited consumption of fried and smoked foods, since frying and smoking produce substances with carcinogenic effects in products;
eating only fresh products, without signs of bacterial or fungal infection;
mandatory inclusion of vegetables and fruits in the diet - up to 5 items daily; preference should be given to citrus fruits, berries, green leafy vegetables, onions, garlic, legumes, green tea is also useful - due to their composition, these products not only stabilize the functioning of the digestive system, but provide antioxidant protection necessary for the prevention of tumor diseases.

A balanced diet helps reduce the risk of developing all cancers, but the most beneficial effect is on the risk of tumor damage to the digestive organs.

Alcohol. Refusal (limiting the amount) of drinking alcohol is necessary due to the fact that ethyl alcohol has a direct damaging effect on the cells of the human body. In addition, alcoholic products contain a lot of toxic substances formed during the production of drinks. In its ability to cause a tumor process, alcohol is equal to tobacco smoke. If a person who abuses alcohol smokes, the carcinogenic effect on the body doubles. Quitting alcohol consumption reduces the risk of developing tumors of the esophagus, stomach, and liver.

Smoking. When smoking tobacco, a huge amount of combustion products and tar enters the body, which stimulate the tumor process. Smoking contributes to the development of cancer of the lip, lungs, larynx, stomach, esophagus and bladder. The fact that out of 10 people suffering from lung cancer, nine are smokers says a lot.

Obesity. Being overweight or obese most often indicates that a person is eating poorly and leading a sedentary lifestyle. Adipose tissue actively participates in hormone metabolism and therefore its excess leads to changes in hormonal levels, and, as a result, an increased risk of hormone-dependent tumors. Normalizing body weight and maintaining it at a normal level helps prevent the development of cancer of the uterus, mammary glands, ovaries, kidneys, esophagus, pancreas, gallbladder (in women), and colon cancer (in men).

Physical inactivity. Active physical activity (fast walking, running, swimming, outdoor games, cycling, skating, skiing, etc.) for at least 30 minutes a day normalizes metabolism, body weight, improves mood, and helps in fighting with stress, depression, improves blood circulation and normalizes immune activity. Adequate physical activity can reduce the risk of developing colon, uterine and breast cancer.

Refusal of abortion. Abortion causes irreparable harm to the entire woman’s body, primarily to the endocrine system, reproductive organs, and is also accompanied by severe mental trauma, which cannot but affect the activity of the immune system. Avoiding abortion can reduce the risk of developing tumors of the uterus, mammary glands, ovaries, and thyroid gland.

Competent contraception. The use of condoms helps prevent unwanted pregnancy, prevent abortion, and prevent sexually transmitted diseases, including HIV infection, viral hepatitis B and C, human papillomavirus infection - diseases that have been proven to be associated with a high risk of tumor pathology. If there are a large number of sexual partners, a condom protects a woman’s body from a massive attack of foreign cells and proteins, thereby protecting her immune system from exhaustion. Thanks to the protective effect of the condom, the risk of developing liver cancer (through protection against hepatitis B and C viruses) and cervical cancer (through the prevention of human papillomavirus infection) is reduced. Low-dose hormonal contraceptives also have an antitumor effect - they protect the woman’s body from cancer of the uterus, ovaries, and rectum.

Fighting stress and depression. The relationship between severe stressful situations, depression and the occurrence of tumor diseases is clearly visible. As trivial as it may seem, optimism and the ability to cope with negatively colored emotional states play a very important role in the prevention of tumors. Some people require professional help in this matter in the form of consultation with a psychotherapist or psychologist.

Careful handling of ultraviolet light. Sun rays often become a factor that triggers the development of tumor diseases. Excessive tanning, both on the beach and in the solarium, and top-less sunbathing can cause the development of melanoma, skin cancer, mammary and thyroid cancer.

Domestic and living conditions. The desire to shorten time and reduce the cost of construction or repairs often leads to the use of non-ecological building materials, which include asbestos, slag, resins, formaldehyde, nitro compounds, etc., which, combined with violations of technical requirements for ventilation equipment, leads to accumulation of harmful compounds in the home (primarily in the air). Acting as absolute carcinogens, these compounds stimulate the development of tumors in all organs and systems of the body.

According to forecasts of the World Health Organization (WHO), during the period from 1999 to 2020, the incidence of malignant neoplasms and mortality from them worldwide will increase by 2 times: from 10 to 20 million new cases per year and from 6 to 12 million registered deaths, respectively. Considering that in developed countries there is a tendency towards a decrease in these indicators (both due to prevention, primarily the fight against smoking, and due to the improvement of methods of early diagnosis and treatment), it becomes clear that the main increase will be in developing countries, which include today Russia should also be included. Unfortunately, in Russia we should expect a serious increase in both the incidence of cancer and mortality from malignant tumors. This forecast is also confirmed by data on the main causes of cancer.

The first places in the structure of the incidence of malignant neoplasms of the male population of Russia are distributed as follows: tumors of the trachea, bronchi, lung (18.4%), prostate gland (12.9%), skin (10.0%, with melanoma - 11.4% ), stomach (8.6%), colon (5.9%). The proportion of malignant neoplasms of the rectum, rectosigmoid junction, anus (5.2%), lymphatic and hematopoietic tissue (4.8%), kidney (4.7%), bladder (4.5%), pancreas ( 3.2%), larynx (2.5%). Malignant tumors of the genitourinary system form a significant group in men, accounting for 22.9% of all malignant neoplasms.

Breast cancer (20.9%) is the leading oncological pathology in the female population, followed by neoplasms of the skin (14.3%, with melanoma - 16.2%), uterine body (7.7%), colon (7. 0%), stomach (5.5%), cervix (5.3%), rectum, rectosigmoid junction, anus (4.7%), ovary (4.6%).

Early diagnosis of malignant neoplasms depends mainly on the oncological alertness of general practitioners and their knowledge, and further tactics in relation to the patient. In 1994 The European Commission for Research on Cancer (EUROPEAN GUIDELINES FOR QUALITY ASSURANCE IN MAMMOGRAPHY SCREENING) at a special conference on the role of the physician and surgeon in cancer screening, highly appreciated the role of the practicing physician, in our country - the general practitioner. The importance of a general practitioner is difficult to overestimate. The constant work of oncology clinics with general practitioners and the population, aimed at the early detection of malignant neoplasms, is an important component that can increase the level of early diagnosis of cancer of various locations.

Improving sanitary educational work, dispensary examination of the population, timely treatment of patients if various pathologies are suspected, and the use of a comprehensive examination of the population will improve the timely diagnosis of malignant neoplasms and treatment results.

Thus, the main task of the doctor in his work on the prevention of cancer pathology is the timely recognition and treatment of precancerous conditions against which cancer develops, as well as the early diagnosis of malignant neoplasms.

Primary prevention

Primary cancer prevention (PCP) should play a leading role in reducing cancer incidence.

Primary cancer prevention (PCP) “is understood as a system of state-regulated social and hygienic measures and efforts of the population itself, aimed at preventing the occurrence of malignant tumors and the precancerous conditions that precede them by eliminating, weakening or neutralizing the effects of adverse factors in the human environment and lifestyle, as well as by increasing the nonspecific resistance of the body. The system of measures should cover the entire life of a person, starting from the antenatal period. First of all, this is the complete elimination or minimization of contact with carcinogens.”

It is necessary to distinguish between individual and state measures for the prevention of malignant tumors.

Individual prevention

Individual prevention involves informing the population about cancer and following a number of rules.

Based on the risk factors for malignant tumors, every person should remember:

●rational nutrition. Pickles and pickled foods should be excluded from the daily diet, as they contain nitrites and nitrates. To prepare foods for future use, it is recommended to use quick freezing instead of canning. This is what played a role in reducing the incidence of stomach cancer in the United States. You should limit your intake of animal fats, smoked and fried foods, and increase and diversify your consumption of fresh vegetables and fruits. During periods of shortage of fresh vegetables and fruits, it is advisable to regularly take synthetic vitamins. Clinical observations have shown that taking vitamins A and E reduces the incidence of gastric epithelial metaplasia of the intestinal type and has a therapeutic effect on pre-tumor changes in the mucous membranes, in particular the oral cavity;

●the dangers of active and passive smoking. Quitting smoking reduces the risk of cancer by 30%;

●endocrine-metabolic disorders. With obesity and multiple abortions, the risk of developing cancer of the reproductive system increases;

●the existence of hereditary forms of cancer. In case of “familial forms” of cancer, timely consultation of the proband’s relatives with a medical specialist is necessary;

●damage from excessive sun exposure;

●the need to maintain oral and genital hygiene;

●the dangers of excessive consumption of strong alcoholic beverages. Low-alcohol and medium-strength drinks, such as table grape wines, do not have such a harmful effect.

Mass prevention

Government measures for primary cancer prevention consist of controlling the content of carcinogenic and radioactive substances in drinking water, food products, air and soil. The state must solve environmental problems by developing and using filters in enterprises that pollute the atmosphere, increasing the efficiency of internal combustion engines in road transport, using environmentally friendly fuel, eliminating occupational hazards in production, etc.

Diagnosed in the early stages, malignant tumors of most organs can currently be cured in 70-100% of patients.

The basis for early diagnosis of malignant tumors is screening. The goal of screening is to reduce mortality from this pathology through active early detection and treatment of preclinical forms of cancer.

Any screening program must meet several mandatory requirements:

●The pathology being studied must be socially significant, i.e. with high morbidity and mortality.

●The screening method must be highly sensitive. Specificity matters less.

●The technique must be accessible to the general population.

●Minimum price and invasiveness of the procedure are desirable.

●The result of screening should be a reduction in mortality from this pathology.

Taking these requirements into account, several oncological diseases were selected for the diagnosis of which it is advisable to create screening programs. These include cancer of the breast, cervix, stomach, colon and rectum, prostate, and lung.

Priority areas for real primary cancer prevention in modern Russia

●Anti-cancer educational work among the population. Creation of a regulatory and methodological basis for primary cancer prevention.

●Cancer prevention in high-risk groups.

●Prevention of occupational cancer.

●Regional prevention programs.

●Training of specialists in the field of project control and improvement of their qualifications.

Areas of primary cancer prevention

Direction of PPR	primary goal
Oncohygienic prevention	Identification and elimination of the possibility of human exposure to carcinogenic environmental factors, correction of lifestyle characteristics
Biochemical prevention (chemoprophylaxis)	Prevention of the blastomogenic effect from exposure to carcinogenic factors by the use of certain chemicals, products and compounds, as well as biochemical monitoring of the effect of carcinogens on the human body
Medicogenetic prevention	Identification of families with hereditary tumor and pre-tumor diseases, as well as individuals with chromosomal instability and organization of measures to reduce the risk of tumors, incl. possible exposure to carcinogenic factors
Immunobiological prevention	Identification of persons with impaired immune status that contribute to the occurrence of tumors, implementation of measures for their correction, protection from possible carcinogenic effects. Vaccinal prevention
Endocrine-age prevention	Identification of dishormonal conditions, as well as age-related disorders of homeostasis that contribute to the emergence and development of tumors, and their correction

When ranking the main causes of cancer incidence, the leading position is occupied by poor nutrition (up to 35%), followed by smoking (up to 32%).

Thus, 2/3 of cancer cases are caused by these factors. Next in decreasing order of importance are viral infections (up to 10%), sexual factors (up to 7%), sedentary lifestyle (up to 5%), occupational carcinogens (up to 4%), alcoholism (up to 3%), direct environmental pollution (up to 2%); family history of cancer (up to 2%); food additives, ultraviolet radiation from the sun and ionizing radiation (up to 1%). About 5% of cancer cases are due to unknown causes.

Nutrition. There are 6 basic principles of an anti-cancer diet, the observance of which can significantly reduce the risk of cancer:

1. Prevention of obesity (excess weight is a risk factor for the development of many malignant tumors, including breast cancer and uterine cancer).

2. Reducing fat consumption (with normal physical activity, no more than 50-70 g of fat per day with all foods). Epidemiological studies have established a direct link between fat intake and the incidence of breast cancer, colon cancer and prostate cancer.

3. The obligatory presence in food of vegetables and fruits, which provide the body with plant fiber, vitamins and substances that have an anti-carcinogenic effect.

These include:

Yellow and red vegetables containing carotene (carrots, tomatoes, radishes, etc.);

Cabbage (especially broccoli, cauliflower and Brussels sprouts); garlic and onion.

4. Regular and sufficient consumption of plant fiber (up to 35g daily),

which is found in whole grains, vegetables, and fruits. Plant fiber binds a number of carcinogens, reduces the time of their contact with the colon by improving motility.

5.Limiting alcohol consumption. It is known that alcohol is a risk factor for the development of cancer of the oral cavity, esophagus, liver and breast.

6. Limit consumption of smoked and nitrite-containing foods. Smoked food contains a significant amount of carcinogens. Nitrites are found in sausages and are still often used by manufacturers for coloring to give products a marketable appearance.

The influence of nutritional factors on cancer development is not well understood and defined. Assessing the potential role of diet entails measuring the contribution of a diet containing various components that may both protect against cancer and increase the risk of cancer. A systematic review-based assessment of the overall impact of dietary guidelines on cancer prevention was published by the World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR). The consumption of fruits and non-starchy vegetables has the greatest preventive effect on reducing the risk of cancer. In particular, it has been proven that sufficient consumption of them reduces the likelihood of developing cancer of the oral cavity, esophagus and stomach. Consumption of fruits, but not non-starchy vegetables, was also significantly associated with a reduced risk of lung cancer.

The difficulty of elucidating the relationship between food intake and cancer risk is demonstrated by examples where observational epidemiological studies (case-control and cohort studies) show an association between diet and cancer risk, but controlled randomized trials do not find such an association. For example, based on population-based epidemiological data, a high-fiber diet has been recommended for the prevention of colon cancer, and a randomized controlled trial of supplementation with dietary fiber (wheat bran) did not show a reduction in the risk of subsequent development of adenomatous polyps in people with a previous history of colon cancer. resection of polyps. As a second example, epidemiological cohort studies and case-control studies found an association between fat and red meat consumption and colon cancer risk, but a randomized controlled trial found no such association in postmenopausal women. These examples do not negate the results of all cohort studies and case-control studies, especially those conducted over many years, but only show the complexity of the problem of studying the effect of diet on the risk of tumor development. Relatively short, controlled, randomized clinical trials are unable to reveal the effect of long-term dietary habits on the risk of developing malignant neoplasms.

Smoking. Numerous scientific studies have established a strong connection between tobacco consumption and cancer. In particular, epidemiological studies have proven that cigarette smoking is a causative factor in the development of cancer of the lung, oral cavity, esophagus, bladder, kidney, pancreas, stomach, cervix and acute myeloid leukemia. At the same time, convincing data have been obtained that an increase in the prevalence of smoking among the population entails an increase in mortality from cancer and, conversely, a decrease in the prevalence of smoking reduces the mortality rate from lung cancer in men.

1. Nitrites, nitrates, salts of heavy metals (arsenic, beryllium, cadmium, lead, nickel, etc.) of drinking water and food products: enhance the effect of carcinogens and are a material for the endogenous synthesis of carcinogens (cytroso compounds)

a) excess body weight is the cause of increased levels of estrogens, synthesized mainly by adipose tissue (peripheral aromatization);

b) stimulation of bile production (changes in intestinal flora, formation of carcinogens from cholesterol and fatty acids)

3. Canned foods, dried fish (contain no nitrates, nitrites), smoked products (contain polycyclic hydrocarbons)

4.Cooked carbohydrates, combining with amines in gastric juice, lead to the formation of nitroso compounds

5). Dflotoxins (peanuts, grains)

According to the Ministry of Health of Russia in the Russian Federation annually about 300 thousand. able-bodied people do not survive about five years of their lives due to tobacco consumption, while economic losses amount to almost 1.5 trillion rubles. Quitting smoking leads to a gradual reduction in the risk of cancer, an increase in life expectancy, and a decrease in overall morbidity and mortality.

Infections. In developing countries, infectious agents are responsible for 26%, and in developed countries - 8% of all cancer cases. Infection with a high-risk strain of human papillomavirus (HPV) (types 16, 18, 31, 33) is considered a necessary event for the subsequent development of cervical cancer, and vaccination against HPV leads to a marked reduction in precancerous lesions. Oncogenic strains of HPV are also associated with cancers of the penis, vagina, anus, and oropharynx. Other infectious agents that cause cancer include hepatitis B virus and hepatitis C virus (liver cancer), Epstein-Barr virus (Burkitt lymphoma), and Helicobacter Pylori (stomach cancer).

Ionizing and ultraviolet radiation. Exposure to radiation, primarily ultraviolet radiation and ionizing radiation, is a well-established cause of cancer. Exposure to solar ultraviolet radiation is the leading cause of skin cancer (non-melanoma), which is by far the most common and most preventable cancer. The most dangerous time to be in the sun is between 10 a.m. and 4 p.m. Staying in solariums to obtain an artificial tan is no less harmful. Avoiding direct sunlight on exposed areas of the body, wearing appropriate summer clothing, wide-brimmed hats, umbrellas, staying in the shade, and using sunscreen are effective measures to prevent skin cancer.

Currently, based on numerous epidemiological and biological studies, it has been convincingly proven that there is no dose of ionizing radiation that should be considered completely safe, for this reason all measures should be taken to reduce the dose of any ionizing radiation to humans, including those associated with medical research (fluorography, radiography, fluoroscopy, computed tomography, radioisotope diagnostics and treatment methods) both in relation to patients and medical personnel. Limiting unnecessary diagnostic and treatment tests associated with the use of ionizing radiation is an important prevention strategy.

Alcohol. The most reliable effect is exerted by excessive consumption of alcohol, especially drinking alcohol, on the development of cancer of the oral cavity, esophagus, breast and colorectal cancer in men. There is less certainty of such a connection between alcohol intake and the risk of liver cancer and colorectal cancer in women.

Physical activity. Increasing evidence suggests that people who are physically active have a lower risk of developing certain cancers than those who are physically inactive and sedentary. The largest and most significant protective effect of physical activity was found in relation to the risk of colorectal cancer. The “probable” category refers to the effect of physical activity on the risk of breast cancer after menopause and endometrial cancer. As with dietary factors, the problem of the influence of physical activity on the development of various cancers is far from being resolved, but it is quite clear that it plays a significant role in the process of oncogenesis. There is evidence to suggest that physical activity is inversely associated with at least several types of cancer that are caused by obesity.

Obesity. Obesity is increasingly recognized as an important risk factor for cancer.

Its connection with the development of postmenopausal breast cancer, esophageal, pancreatic, colorectal, endometrial and kidney cancer has been convincingly proven. Evidence has been obtained that obesity is a risk factor for the development of gallbladder cancer. But at the same time, it should be noted that there are no studies on the effect of reducing excess body weight on mortality from malignant neoplasms.

Vitamins and biologically active food additives. Vitamins and dietary supplements are preventive interventions with unproven effectiveness.

Environmental factors and harmful substances. Several associations between environmental pollutants and the development of lung cancer have been clearly established, including through second-hand tobacco smoking and air pollution, especially asbestos dust. Another environmental pollutant that has been causally linked to skin, bladder and lung cancers is inorganic arsenic at high concentrations in drinking water. Many other environmental pollutants, such as pesticides, have been evaluated for their risk of cancer in humans, but the results have been inconclusive.

Occupational hazards Some cancers induced by chemicals are classified as occupational: cancer of workers in hot shops, winemakers (cancer of the hands and feet), cancer of those working with paraffin (cancer of the hands and scrotum), sailors, peasants, those exposed to a lot of air (cancer of the face, hands), cancer when working with aniline substances (cancer of the urinary tract), x-rays (for doctors, X-ray laboratory personnel), with resins, pitch (for shoemakers - cancer of the fingers), rubber (for those working with rubber cables - skin and bladder cancer), in contact with asbestos, chromium, generator gases (lung cancer - contact with asbestos, beryllium, uranium or radon). It is also important that in order to eliminate occupational carcinogenic exposure, in many cases it is sufficient to carry out local measures aimed at a specific workshop, technological process, etc. Therefore, the greatest successes in the world have been achieved precisely in the field of prevention of malignant tumors associated with the profession.

The main tasks of sanitary and hygienic certification of carcinogenic enterprises

●Creation of territorial regional and Federal databases on carcinogenic enterprises.

●Creation of territorial regional and Federal registers of persons in contact with occupational carcinogenic factors.

●Carrying out preventive measures at enterprises.

Genetic factors. A small number of tumors can occur as genetically determined diseases. Dependence on “tumor” genes is associated with the appearance of congenital or hereditary tumors. They have been proven for approximately 50 types of tumors. Dominantly inherited tumors include basal cell carcinomas, acoustic neuroma, osteochondromas, multiple lipomas, cervical polyposis, and neurofibromatosis. Plasmocytomas and embryonal nephromas are considered recessively inherited.

The association between “tumor” and other genes turns out to be interesting, for example, an increase in the frequency of stomach cancer in people with blood group A (II). Hereditary neoplasms can occur as congenital or develop immediately after birth, but can develop in older children or even adults.

Relationship between carcinogens

Another aspect to consider is the relationship between carcinogens. For example, it has been shown that increased alcohol intake greatly increases the risk of esophageal cancer caused by a risk factor such as smoking. Alcohol, by itself, can facilitate the transport of tobacco or other carcinogens into cells or susceptible tissues. Multiple links can be traced between certain carcinogens, such as between exposure to radon decay products and smoking among uranium mine workers. Some exogenous agents may promote the development of cancer caused by other agents. This, in particular, applies to the role of dietary fats in the development of breast cancer (obviously due to an increase in the production of hormones that stimulate the mammary gland). The opposite effect may also occur. For example, vitamin A delays the development of lung cancer and, possibly, other cancers initiated by tobacco smoking. Similar relationships can occur between exogenous factors and the constitutional characteristics of the body. In particular, genetic polymorphism of enzymes involved in the metabolism of carcinogens or DNA repair is an important factor that determines individual susceptibility to the action of exogenous carcinogens.

From a cancer prevention perspective, the significance of the relationship between carcinogens is determined by the fact that eliminating exposure to one of two (or more) interrelated factors can provide a greater reduction in cancer incidence than would be predicted by the magnitude of exposure to that agent in isolation. For example, quitting smoking can almost completely eliminate the high incidence of lung cancer among workers in the asbestos industry (although the incidence of mesothelioma will remain almost unchanged).

Secondary prevention

Aimed at identifying and eliminating precancerous diseases and identifying malignant tumors in the early stages of the process. Tests that make it possible to effectively identify precancerous diseases and tumors include: mammography, fluorography, cytological examination of smears from the cervix and cervical canal, endoscopic examinations, preventive examinations, determination of the level of tumor markers in biological fluids, etc.

The development of early diagnosis and screening programs is one of the priorities for the development of oncology and can significantly improve treatment results. Regular preventive examinations and examinations in accordance with age (or risk group) can prevent the occurrence of a malignant tumor or identify the disease at an early stage, allowing for effective organ-preserving specialized treatment.

Disease	Research method, frequency	Description	Age of onset
Cervical cancer	Papanicolaou test, once a year	During an examination by a gynecologist, a smear of the vaginal and cervical mucosa is taken. This method also makes it possible to diagnose benign and inflammatory diseases, as well as endometrial cancer.	3 years after the start of sexual activity
Mammary cancer	Mammography, once a year	X-ray examination of the breast
	Clinical examination, once every 3 years	Palpation examination by a mammologist
	Self-examination, once a year	Palpation examination by a mammologist
Cancer of the colon and rectum (colorectal cancer)	Fecal occult blood test, once a year	Laboratory testing of feces for the presence of blood. If the result is positive, a colonoscopy is performed
	Sigmoidoscopy and/or sigmoidoscopy once every 3 years	Endoscopic examination of the intestine with a short tube with a built-in camera
	Colonoscopy, once every 10 years	Endoscopic examination of the intestine with a flexible tube with a built-in camera
	Finger examination, once a year	Examination of the rectum with a finger
Prostate cancer	Blood test for PSA (prostate-specific antigen), once a year Digital examination of the rectum, once a year	Digital examination, also effective in diagnosing rectal and anal cancer

Listed above are screening methods that are effective in early diagnosis of cancer and improved treatment outcomes for the entire population, regardless of the presence of risk factors.

However, there are other common cancers for which there is not yet enough data on the effectiveness of preventive examinations for the entire population, but screening is certainly indicated for individuals with certain risk factors. Screening methods were listed that are effective for early diagnosis of cancer and improvement of cancer treatment outcomes for the entire population, regardless of the presence of risk factors.

Tertiary prevention

It consists of preventing relapses and metastases in cancer patients, as well as new cases of malignant tumors in cured patients. For the treatment of a malignant tumor and tertiary cancer prevention, you should only contact specialized oncological institutions. An oncology patient is registered with an oncology institution for life and regularly undergoes the necessary examinations prescribed by specialists.

Currently, one of the youngest and most promising branches of preventive oncology is chemoprevention of malignant tumors - reducing cancer morbidity and mortality through long-term use of special oncological prophylactic drugs or natural remedies by healthy people or persons from groups at increased risk of cancer. Chemoprophylaxis must be used in combination with other preventive measures.

A separate area of prevention in patients with malignant neoplasms is the prevention of complications of chemotherapy that arise due to the low selectivity of the action of most of the drugs used for these purposes. One of the most common complications of chemotherapy is toxic liver damage. Unfortunately, in oncological practice, a drug that adversely affects the liver cannot always be withdrawn or replaced with another, safer one without creating an immediate or delayed threat to the patient’s life. One way out of this difficult situation is the prophylactic use of drugs with hepatoprotective properties, among which S-adenosyl-L-methionine has a good evidence base for its high clinical effectiveness.

Currently, cancer risk groups are usually divided into 5 categories based on the degree of risk increase.

1.Practically healthy persons of any age with a family history of cancer and people over 45 years of age.

2.Practically healthy persons who have been or are exposed to carcinogenic factors. These include smokers, persons in contact with occupational and household carcinogenic factors, those who have suffered ionizing radiation exposure, and carriers of oncogenic viruses.

3. Persons suffering from chronic diseases and disorders that increase the risk of cancer: obesity, immunosuppression, atherosclerosis, hypertension, type 2 diabetes mellitus, COPD, etc.

4. Patients with obligate and facultative precancerous diseases. The latter are more common and only increase the likelihood of cancer.

5. Cancer patients who have undergone radical treatment for cancer. (This category of patients in accordance with the order of the Ministry of Health of Russia dated November 15, 2012 No. 915n

“The procedure for providing medical care to the population in the field of oncology” - they are subject to lifelong dispensary observation in an oncology clinic. If the course of the disease does not require a change in patient management tactics, clinical examinations after treatment are carried out: during the first year once every three months, during the second year - once every six months, thereafter - once a year).

SAMPLE TEST TASKS

Please indicate one correct answer

1. Rational nutrition for the prevention of cancer pathology, everything except:

a) to prepare for future use, use freezing of food

b) limit the intake of pickles and marinades

c) limit the intake of animal fats

d) limit fruit intake

2. Modifying factors of carcinogenesis do not include:

a) profession

b)lifestyle

c) age

d) bad habits

e) nature of nutrition

3. Risk factors for cancer pathology:

a) obesity

b) multiple abortions

c) alcoholism

d) smoking

d) that's right

SITUATIONAL TASK

A 34-year-old man worked for 14 years as a molder in a foundry. Occupational hazards: quartz-containing dust (concentration 4 times higher than the maximum permissible concentration), increased indoor air temperature. Smokes up to a pack of cigarettes a day for 13 years. Anamnesis of a patient with pulmonary tuberculosis (cure).

Objectively: Auscultatory examination reveals isolated dry rales in the lungs. Heart sounds are clear and rhythmic. Heart rate 75 beats/min. The abdomen is soft and painless on palpation. Stool and urine output are normal.

Survey results

Survey X-ray of the chest organs: a deformation of the pulmonary pattern due to small-spotted nodular-type shadows was revealed.

EXERCISE

1. Identify risk factors for the development of cancer pathology in the patient.

2.Calculate the smoker's index?

3. Patient management tactics.

SMOKING. Based on an expert assessment of experimental and epidemiological studies of the carcinogenicity of smoking conducted by IARC, it has been proven that smoking is etiologically associated with a number of malignant tumors, namely the lip, tongue, other parts of the oral cavity, oropharynx, hypopharynx, esophagus, pancreas, larynx, trachea, bronchi and lungs, bladder and kidneys. The incidence of these forms of cancer in the Russian Federation is more than 50% of the incidence of all malignant tumors among men. Among women, the percentage of malignant tumors etiologically associated with smoking is much lower and does not exceed 10%.

Along with smoking, excess alcohol consumption plays a role in the etiology of some of the above forms of cancer, namely cancer of the oral cavity, esophagus, pancreas and larynx. The latter factor, being an independent risk factor for the above forms of cancer, enhances the effect of smoking.

The attributable risk of smoking for individual forms of cancer, that is, the percentage of all cases of a given cancer that is etiologically associated with smoking, varies. According to the most conservative estimates, the direct cause of 80-85% of all cases of lung cancer is smoking. Smoking and excessive alcohol consumption are responsible for 80% of lip and oral cavity cancers.75 % esophageal cancer, 30% pancreatic cancer, 85% laryngeal cancer and about 40% bladder cancer.

Quitting smoking will lead to a reduction in the incidence of malignant tumors by 25-30%, which for Russia amounts to 98,117 thousand cases of malignant tumors per year.

NUTRITION. Nutritional components play an important role in the occurrence of a number of forms of malignant tumors. At least one third of all malignant tumors are related to diet.

A number of dietary components, namely animal fats, are likely to increase the risk of colorectal cancer, and possibly breast, uterine, ovarian and prostate cancer. While vitamins, primarily vitamin C, A, beta-carotene, as well as foods rich in these vitamins, reduce the risk of malignant tumors, including oral cancer of the esophagus, stomach, larynx, lung, bladder, colon intestines, and possibly the mammary gland.

In addition, salted, smoked and canned foods may contain various carcinogenic substances, namely N-nitrosoamines and polycyclic aromatic carbohydrates (PAHs). There is reason to believe that nitrosamines, as well as their precursors (nitrates, nitrites) in food, are associated with an increased risk of cancer of the esophagus and stomach. An increased risk of stomach cancer is observed among people who consume a lot of salt, mainly through foods that are preserved by salting. Despite the fact that at present our knowledge is not sufficient to accurately indicate all the components of nutrition that contribute to the development of cancer or, conversely, reduce the risk of its development, there is no doubt that a change in diet towards increasing the consumption of vegetables, herbs and fruits and reducing the consumption of fat and foods rich in fat will lead to a reduction in the incidence of malignant tumors. Food labeling for essential ingredients plays an important role in implementing these recommendations.

An essential component of cancer prevention through dietary modification is improving food storage methods, with limited use of salt for food preservation.

PROFESSIONAL CARCINOGENS. Available epidemiological data, as well as an assessment of the carcinogenic risk to humans of occupational factors conducted by the International Agency for Research on Cancer have shown that 29 substances used in industry or industrial processes increase the risk of cancer in humans. Some of them are widespread both in highly industrialized countries and in countries with a relatively low level of industrial development. In addition, experimental and epidemiological studies have shown that about 100 substances that people come into contact with in production conditions are also suspected of being carcinogenic.

The proportion of cancer cases attributable to occupational exposure is difficult to estimate, but estimates range from 1 to 4% all malignant neoplasms. However, there is considerable variability in the proportion of malignancies associated with occupational exposure, which may be significant in industrialized regions. For example, the incidence of bladder and lung cancer can be very high in regions with developed industry and poor hygienic exposure controls.

Malignant neoplasms of occupational origin, especially when the cause is established, are more easily preventable with the help of appropriate technological measures than malignant neoplasms associated with household factors. Carcinogenic occupational factors are rarely presented in the form of one specific substance. More often we are dealing with complex mixtures, not all of whose components may be known.

To reduce the incidence of occupational cancer, it is recommended

1. Eliminate known occupational carcinogens from production or reduce their level, at least to the standards adopted in the European Economic Community, with constant monitoring.

2.. Make public all known occupational carcinogens, including their appropriate labeling.

3. Determine the number of workers exposed to known occupational carcinogenic factors, and establish the prevalence of these factors.

4. Regulate internationally the transfer and use of carcinogenically hazardous industries and technologies.

5.Create conditions for economic incentives for the design and construction of “clean” enterprises and improvement of hygienic conditions in existing enterprises.

AIR POLLUTION. Epidemiological evidence suggests that high levels of urban air pollution and proximity to certain types of industrial plants, such as ferrous and non-ferrous metals, may be associated with an increased risk of lung cancer. Ambient air pollution may play a role in the development of other forms of malignant tumors.

The main carcinogenic air pollutants include polycyclic aromatic hydrocarbons (PAHs), asbestos and some metals. Benz(a)pyrene (BP) has been adopted as an indicator of PAH air pollution. The main sources of air pollution are enterprises of the metallurgical, coke-chemical, oil refining and aluminum industries, as well as thermal power plants and road transport. Epidemiological data indicate an increased risk of lung cancer due to ambient air pollution. A study conducted in 26 industrial cities of the Russian Federation showed that the incidence of lung cancer among men correlates with indicators of air pollution. However, the same study showed that the correlation is better with indicators characterizing the levels of consumption of tobacco products in these cities.

Based on analytical epidemiological studies conducted in a number of foreign countries, it can be concluded that after taking into account smoking, the relative risk of lung cancer associated with air pollution does not exceed 1.5. The greatest increase in risk (1.6 and 2.0) was found in people living near metallurgical plants. An increased risk of lung cancer in women living near a smelter was associated with levels of arsenic air pollution. In all of these studies, smoking and occupational employment in the metallurgical industry were taken into account when calculating relative risk.

Based on calculations made in epidemiological studies carried out in Krakow, it can be said that 4.3% of lung cancer in men and 10.5% in women is caused by air pollution. The same study showed that 74.7% and 20.6% of lung cancer in men and 47.6% and

8.3% in women is caused by smoking and occupational exposure to carcinogens, respectively. Similar estimates were obtained in a number of other epidemiological studies conducted in other countries.

Levels of PAHs in atmospheric air significantly exceed the maximum permissible concentration (1 ng/m3). For example, a metallurgical plant and a coke plant emit more than 2 kg of BP per day, and oil refineries emit more than 3 kg. The concentrations of BP in the emissions of these industries are extremely high, both for the working area and for populated areas. The dispersion of emissions beyond the border of the sanitary protection zone creates an excess of the maximum permissible concentration for coke production by 5-100 times, and for oil refineries by 10 times. Exceeding the MPC extends up to a distance of 10 km from enterprises. In some areas of Moscow, the average daily concentration of BP exceeds 20ng/m3, and the one-time maximum concentration is 100 ng/m3. It has been shown that exposure to other carcinogenic factors, such as smoking, may be aggravated by air pollution.

The difficulty of interpreting epidemiological data on the relationship between air pollution and the risk of malignant tumors can be explained by the inaccuracy of data on the levels of carcinogens in the air, as well as methodological problems associated with the need to separately assess the impact of various factors (air pollution, smoking, occupation) on the risk.

Although there is some uncertainty about the impact of air pollution on the risk of malignancy, measures aimed at further reducing emissions of carcinogens are warranted, in accordance with WHO policies in this area.

It is necessary to conduct epidemiological studies in heavily contaminated areas of Russia using methods that allow a quantitative assessment of the risk of developing malignant tumors.

Measures to prevent malignant tumors associated with air pollution by occupational carcinogens should be aimed at reconstructing enterprises that are the main source of air pollution, taking into account technology to reduce emissions, as well as control of vehicle emissions. In a number of cases, it will be necessary to raise the question of replacing outdated equipment, which has not met modern hygienic requirements for a long time.

IONIZING RADIATION. Ionizing radiation is carcinogenic to humans and leads to the development of almost all forms of malignant tumors. Detailed data on the carcinogenicity of various types of radiation (a, gamma, neutrons) and the “dose-dependence” of its effect were obtained as a result of epidemiological studies of the population of Hiroshima and Nagasaki, groups of people exposed to irradiation for medical purposes and among mine workers exposed to radon and products of its decay. A “dose-dependent” curve of radiation carcinogenesis has been described for various types of radiation. In addition, it was found that the carcinogenicity of a- rays is significantly higher than that of gamma rays.

In Hiroshima and Nagasaki, the peak incidence of leukemia was reached seven to eight years after the bombing, but the increased risk of leukemia persisted for more than 40 years. The increase in the incidence of solid tumors occurred much later: the risk was higher for those exposed to radiation at an early age.

Relatively recently, evidence has been obtained of an increased risk of cancer in people exposed to ionizing radiation in utero. In addition, it has been shown that the risk of leukemia is increased in children of fathers working at nuclear power plants and exposed to low doses of radiation. Most likely, the latter effect is the result of the mutagenic effect of radiation on germ cells.

Despite the accumulated experience and the possibility of extrapolation based on mathematical models, it is quite difficult to reliably predict the incidence of tumors among the exposed population when the radiation situation was different from the already observed situations. For example, as a result of the Chernobyl accident, the population was and, apparently, continues to be exposed to long-term effects of low doses of radiation on the entire body, the sources of which are soil, water and food. While the victims of the atomic bombings in Hiroshima and Nagasaki received external α-irradiation with an exposure duration of several seconds. Miners in the mines were exposed for a long time to a-particles that entered the body through the respiratory tract. The above suggests that it is necessary to constantly monitor the health of the population who have received increased doses of radiation, including measures for the early detection of malignant tumors. In addition, primary prevention measures should be implemented aimed at eliminating the influence of other known chemical and physical carcinogens on these people, namely, smoking, occupational carcinogens, as well as the use of radiological diagnostic methods. In addition, it is necessary to create a diet for them that reduces the risk of malignant tumors. Such primary and secondary prevention measures can lead to significant reductions in cancer incidence and mortality in populations exposed to ionizing radiation.

A significant increase in the risk of lung cancer in non-smoking women was revealed depending on the levels of radon exposure in residential premises; it can be assumed that some cases of lung cancer can be prevented by reducing indoor radon exposure. These measures should primarily be aimed at the correct selection of areas for building houses, as well as the elimination of building materials that may be sources of radon.

And yet, a person receives the most significant doses of radiation as a result of diagnostic and therapeutic measures (excluding extreme situations). Therefore, limiting the use of radiological diagnostic methods only to medical indications, using the lowest possible doses, will also lead to a reduction in the incidence of malignant tumors.

OTHER RISK FACTORS. In the etiology of malignant skin tumors, ultraviolet radiation plays a dominant role. Therefore, avoiding excessive exposure to sunlight, especially for people with very fair skin, will reduce the incidence of various forms of malignant skin tumors, including melanoma. The production and use of chlorofluorocarbon aerosols should be limited and ultimately eliminated because they deplete the ozone layer of the atmosphere and consequently increase levels of ultraviolet radiation.

In order to limit the spread of infectious agents that contribute to the development of cervical cancer, as well as AIDS and other diseases etiologically associated with viral infection, sex education programs should be introduced, primarily in schools, and the availability of cheap and good quality condoms should be ensured. Proper testing and processing of donated blood can significantly limit the risk of cancer and other diseases associated with blood-borne viruses. Blood testing is necessary for at least hepatitis B and HIV viruses, and possibly HTLV-l.

Thus, there is now convincing scientific evidence on the risk factors for malignant tumors, on the basis of which more than half of all cases of this disease can ultimately be prevented. However, cancer prevention measures, namely smoking control, dietary modification, hygienic measures to remove carcinogenic substances from enterprises and the environment in general, reducing exposure to ionizing radiation, and controlling viral infections require significant efforts from the state and society as a whole.

AGENTS AND INDUSTRIAL RECOGNIZED CARCINOGENIC TO HUMANS IN IARC MONOGRAPHIES (GROUP 1)

Agent/industrial process	Primary source of professional exposure	The main organ in which the carcinogenic effect is registered
Aluminum production		Lung, bladder
4-aminobiphenyl	Dye production	Bladder
Arsenic and its compounds	Production and use of arsenic-containing insecticides; mining; copper smelting	Leather; lung; liver
	Extraction; production and use of insulating materials; textile industry; construction, repair of ships; cladding, covering	Lung; mesothelioma of the pleura and peritoneum
Auramine, production		Bladder
	Rubber industry; shoe industry; oil refining
Benzidine	Dye production	Bladder
Bis(chloroethyl) ether and chloromethyl ether (technical)	production
Fuchsin, production		Bladder
Mineral oils (raw and pre-processed)	Metalworking, jute processing
Mustard gas (mustard gas)	production
2-naphthalamine	Dye production	Bladder
Nickel and its compounds	Nickel purification	Nose; lung
	Mining industry
Rubber industry		Leukemia; bladder
Shale oils	Shale oil production
	Chimney sweeps
	Production and use	Lung; pleural mesothelioma
Vinyl chloride	Production and polymerization	Angiosarcoma of the liver
Shoe production and repair
Chromium (hexavalent chromium compounds)	Production and use of pigments; chrome plating; production of chromium alloys; stainless steel welding
Coal gasification
Coal tar pitch, tar/tar	Coal distillation; proprietary fuel; roofing; paving	Leather; larynx; lung; oral cavity; bladder
Coke production		Leather; lung; bud; bladder
Furniture making
Hematite mining (underground) with radon exposure
Iron and steel smelting
Production of isopropyl alcohol (technology using strong acids)