The first signs and symptoms of malignant tumors. Cancer. Causes of malignant tumors. Oncology With the emergence of malignant neoplasms, such a disease develops

Mysteries of the occurrence of malignant tumors

Malignant tumors are a very ancient disease. This is evidenced by the findings of paleontologists (traces of various tumors were found in animals that lived many thousands and millions of years ago). In the Ebers papyri and in the writings of the greatest physician of antiquity, Hippocrates, even descriptions of methods for treating certain tumors have been preserved. Tumor changes in the bones and tissues of preserved Egyptian human mummies have been carefully studied and described by modern experts.

The problem of the occurrence of malignant tumors, widely known under the terrible name - cancer, is still the subject of persistent research by scientists. If for normal cells of organs and tissues the pattern is organized, systemic development and reproduction with the preservation of specific functions important for the normal functioning of the body, then a cancer cell dramatically changes its forms and functions. Using a microscope, specialists can easily distinguish the structure of a normal cell from a cancerous one.

One of the methods for recognizing cancer is built on this, when doctors take pieces of a tumor, and histologists make microscopic preparations, stain them with various paints and give an accurate conclusion. This is often done during surgery, when the surgeon needs to immediately find out the nature of the tumor: malignant or benign.

Tumor (cancerous) cells have characteristic features. A cancerous tumor is made up of many malignant cells that multiply randomly, sometimes destroying normal tissue very quickly. Consequently, cancer cells are not only anarchic in their behavior, but also very aggressive. Malignant tumors, for example, in stomach cancer, when rejected, can be carried to the liver or other organs, causing their damage and degeneration (this is called metastases). Here the same process of disorderly and uncontrollable development, tumor formation and irreversible changes begins again.

When and at what stage of cell life do these tragic changes occur? Under the influence of what does the body suddenly begin to experience rapid, uncontrolled growth of cells in various organs and tissues, leading to the formation of malignant tumors? How to prevent it and successfully treat the patient? These and many other questions are awaiting resolution. They are studied by biologists, doctors, geneticists, chemists, biochemists, physicists, botanists, zoologists, representatives of a number of other sciences and even technology.

Tumors are widely found in nature among plants, lower invertebrate animals, cold-blooded and warm-blooded animals, and in humans. Tumors can be benign or malignant; they affect a wide variety of organs and tissues. We can say that humans have tumors of all organs and tissues. Do living things or substances cause cancer?

When microbes were discovered - the causative agents of numerous infectious diseases, it was natural to assume the existence of some microbes that cause cancer. Their search began. Indeed, a variety of microbes began to be found in tumors.

Each discovery was a sensation; it seemed that the cause of cancer had been found, but rigorous testing did not confirm these discoveries. It turned out that in tumors, especially those undergoing decay, many random microbes are always found, most often entering the affected tissue from the outside.

Of great interest were studies that made it possible to transplant tumors using extracts from them filtered through bacterial filters, i.e., cell-free filtrates. We remembered the discovery of filterable viruses by D.I. Ivanovsky. The idea arose about the possible presence of special viruses in tumor filtrates that passed through bacterial filters. Are viruses causative agents of tumors? An interesting, truly brilliant idea is that at the dawn of virology, back in 1909, I. I. Mechnikova expressed it in the article “International meeting in Paris on the issue of cancer.”

The great scientist wrote: “At least one of the causes of malignant tumors comes from outside, falling on the soil of the body, which is especially favorable for their development. Hence the probability that there is some kind of contagious origin of these tumors, which, like the infections of infectious diseases, consists of tiny organisms that enter our body from the outside, from the outside world... For now we have to put up with the fact that the cancer microbe is one of these contagious beginnings that cannot be detected even by the strongest magnifications of the best microscopes... For the formation of malignant tumors, a combination of several factors is needed, one of which comes from the outside, while others are inherent in the body itself.” Once again and more definitely on the same issue, the scientist spoke out in his speech at the festival in honor of Darwin in Cambridge in 1909. “It is very likely, therefore,” said I. I. Mechnikov, “that human cancers also owe their origin to some -a virus that is being diligently searched for, but has not yet been discovered.”

So, the ability to transplant tumors using filtrates that do not contain either microbes or cancer cells has suggested that viruses are the culprits in causing cancer. Only they can pass through bacterial filters that do not allow even the smallest bacteria to pass through. But how can we connect with this other facts that became known many years before such views arose? For example, scientists have already described “chimney sweep cancer.” This disease occurred in chimney sweeps who had to climb into chimneys coming from fireplaces and clean them. The harsh professional conditions of this work caused skin irritation. Soot, resins and other chemical products remaining after incomplete combustion of fuel penetrated into the resulting abrasions and cracks. As a result of such constant skin irritations and the influence of certain chemicals, warty growths appeared on the skin, often turning into skin cancer.

This is how it became known about the influence of chemicals, in particular coal tar, on the occurrence of cancer. Scientists moved on to animal experiments. Only experiments could shed light on the nature of this process. All over the world, the effects of coal tar and its role in the occurrence of skin cancer began to be studied in animals. This was proven by Japanese scientists K. Yamagiwa and K. Ishikawa in experiments on rabbits. Repeatedly smearing coal tar on rabbits' ears caused cancer. This was an important step in the experimental study of cancer, but as is usually the case in science, one discovery causes a “chain reaction” of new searches. What is contained in coal tar? This complex product of coal distillation contains various chemicals. Which one is dangerous and why? Collaborative work between oncologists and chemists began, which led to the discovery of so-called carcinogenic substances that contribute to the occurrence of cancer. At first it turned out to be the hydrocarbon 3,4-benzpyrene, and later others were identified.

In the external environment, in particular in the air, with incomplete combustion of fuel, benzopyrene may be present in concentrations that are dangerous to humans. From these experimental observations, it was advisable to draw a conclusion about the protection of atmospheric air and the elimination of carcinogenic substances from it, products of incomplete combustion of not only fuel in furnaces, but also in various engines.

In addition to skin cancer of chimney sweeps, skin cancer also occurred in people who worked in the dry distillation of coal; cancer of the bladder and urinary tract was one of the occupational diseases in people working in certain branches of the aniline dye industry. Thus, in addition to benzpyrenes, new carcinogenic benzanthracenes, benzphenanthrenes and many other chemical substances, a number of organic compounds, inorganic salts, etc. were discovered. What is common to all these numerous, but different in their chemical composition, substances is the ability, when they enter from the outside, to the body to cause or influence the occurrence of a number of malignant tumors. It should be added that statistics convincingly show that lung cancer is more common among smokers - men and women. There are known cases of the disease in workers who applied luminescent dyes to clock hands and various luminous devices using brushes. For “convenience,” the brushes were moistened with saliva and simply licked. Only clarification of such details made it possible to understand cancer among workers in this industry and to find methods for preventing the disease.

All these discoveries turned out to be very important. But much remains unclear about the mechanism of action of carcinogenic substances. Scientists were interested in the question of whether tumors would arise if carcinogenic substances were introduced naturally, that is, with food through the gastrointestinal tract, or with air through the respiratory tract. Indeed, some fats exposed to high temperatures caused tumors of the stomach, intestines, and liver in laboratory animals. By forcing mice to inhale air with soot from chimneys or tar dust, tumors were obtained in the animals' lungs. The experiments of the famous Soviet scientist L.M. Shabad aroused great interest, who for the first time proved that an extract of the liver of a person who died of cancer, when injected under the skin of mice, caused tumors in them.

Thus, it was concluded that substances that cause cancer, i.e., carcinogenic substances, can be formed in the human body. Based on numerous facts, L. M. Shabad put forward the theory that carcinogenic substances, when formed in the body, can cause the occurrence of malignant tumors. How can the emergence of “radiologist’s cancer” be related to this? Observations have emerged that scientists, radiologists and x-ray technicians who worked with X-rays for many years and did not take measures to protect themselves from these rays also developed skin cancer. Measures to protect against X-rays were developed, and occupational disease ceased. In addition, in experiments on rats, skin cancer was also caused by long-term exposure to ultraviolet rays to areas of the skin less protected by fur, such as the ears. In Japan, in the areas of Hiroshima and Nagasaki, after the Americans dropped atomic bombs there, leukemia (cancer of hematopoietic tissue) became more frequent. The famous Soviet oncologist, Academician of the USSR Academy of Medical Sciences N.N. Petrov, and his colleagues carried out an interesting experiment on monkeys. Scientists inserted small ampoules containing several millionths of a gram of radium into their bones. A few years later, the monkeys developed cancer (bone sarcoma) around the ampoule under the influence of radium rays.

Academician of the Academy of Sciences of the Ukrainian SSR R. E. Kavetsky and N. M. Turkevich proved the extremely important relationship between viral and hormonal factors influencing the occurrence of mammary gland cancer in mice. This means that disturbances in the body’s hormonal activity can apparently contribute to the activation of tumor-producing viruses and the development of tumors.

So, tumors can arise as a result of various carcinogenic substances entering the body from the outside; they can form for a number of reasons in the body itself, as well as under the influence of various radiation exposures. But how do they work? Directly, directly, being the cause of malignant tumors, or do they create a precancerous condition by activating other factors, in particular viruses?

The outstanding Soviet researcher L.A. Zilber believes that carcinogenic substances, while not the actual cause of the transformation of a normal cell into a tumor cell, create the conditions under which this transformation becomes possible. Academician of the Academy of Sciences of the Ukrainian SSR R. E. Kavetsky and his colleagues point out: “It can be assumed that both factors (carcinogenic substances and viruses) play a role in the occurrence of cancer, and carcinogenic substances prepare cells for the penetration of a virus into them. The final resolution of this problem is associated with the general successes in studying the nature of viruses, as well as with the use of modern research methods to study tumor-producing viruses: an electron microscope with a magnification of up to 100,000 times, ultracentrifuges, virus isolation, new immunobiological research methods, etc.”

Among the hypotheses and facts, one cannot help but focus on a new interesting observation. We are talking about aflatoxin.

The term “aflatoxins” appeared relatively recently. If part of this term (toxins) does not need explanation, then “afla” requires decoding. It comes from the name of the microscopic mold fungi Aspergillus flavus (“flavus” means yellow in Latin). Let's connect the first letter (A) of the first word and three letters (fla) of the second and we get - afla, add - toxins. These will be the poisons of the yellow fungus aspergillus - aflatoxins.

The group of pigment (color) microbes has long been well known in microbiology. Microbial pigments come in all sorts of colors - red, green, black, blue, purple, yellow, and orange. The mold Penicillium multicolor (translated as multicolor) was even isolated from the soil, producing pigments of red, purple, pink, yellow, orange and dark brown. This feature of this mold depends on the reaction of the environment. The reaction changes, for example from acidic to alkaline, and the color of the pigment also changes. Sometimes pigment formation allows microbiologists to distinguish microbes from each other. Thus, among the pyogenic microbes, staphylococci, there are different colors: golden, lemon yellow, white, etc.

Surgeons are also interested in pigmentation. They often notice that the bandage or pus on the wound suddenly begins to turn green. This is extremely unpleasant, because it indicates that blue-green pus bacteria have entered the wound and need to be eliminated. Treatment of the sick or wounded becomes difficult. Among the sarcinas commonly found in the air, there are bright yellow, orange, pink, etc.

A colored microbe, Bacterium prodigiosum, has become notorious. This is a completely harmless microbe found in the air. It has the interesting property of producing a bright red pigment. When Bacterium prodigiosum gets on food products, especially starchy ones, located in damp rooms, they multiply greatly and color the product blood-red. Thus, in ancient times, superstitious ideas arose about “bleeding bread” and “bloody spots”. Their appearance on bread was considered a “sign of heaven,” various misfortunes and troubles were expected, and the culprits were looked for. These superstitions once cost the lives of many thousands of innocent people. The Inquisition accused them of witchcraft and “for the glory of God” killed, tortured, and burned them at the stake.

Currently, any schoolchild working in a circle of young microbiologists can reproduce this “miracle” and, in addition, obtain cultures of many other microbes that produce pigments of a wide variety of colors.

By exposing these kinds of “miracles,” science has discovered that coloring substances—microbe pigments—may even be useful in the treatment of various infectious diseases.

So, back at the end of the 19th century. employee of the Military Medical Academy N.P. Tishutkin proved the possibility of using Bacterium prodigiosum for the treatment of scab. Professor B.I. Kurochkin, who studied Bacterium prodigiosum for many years, successfully treated festering wounds.

In the USSR and in other countries of the world, a wide variety of microbes have been found and studied, producing various pigments that have the remarkable property of having a detrimental effect on many pathogenic microbes that cause diseases in humans and animals. Professor N.A. Krasilnikov obtained the drug mycetin from the purple actinomycete, which can kill microbes - causative agents of purulent-inflammatory diseases - staphylococci, as well as tuberculosis and diphtheria bacteria.

The coloring substances of microbes - pigments - are their unique “weapons” of defense or attack. One microbe, producing pigments, stores them in its cytoplasm, others secrete them out. Some pigments dissolve well in water, others only in special solvents. For many years, scientists have been studying pigment microbes, trying to put them at the service of humans.

In 1961, a report appeared that a pestilence among turkeys had begun in certain parts of the country in England. Within three months, more than 100 thousand of them died. Such an event could not go unnoticed and required a careful study of yellow aspergillus that got into the feed, and the toxin, aflatoxin, had a disastrous effect on turkeys. There were good reasons for microbiologists to be concerned.

The investigation established that the death of young turkey poults occurred only in those farms where groundnut flour was added to the feed. But no matter how much this flour was examined, no toxic impurities were found. Only after scientists found the mold Aspergillus flavus and isolated aflatoxin was the cause of the death of the turkey poults established. A tiny amount of this poison was enough to quickly kill turkey poults. Knowledge of pigment microbes has expanded. It turned out that they produce not only medicinal substances, but also poisons.

It soon became known that aflatoxin was dangerous not only for birds, but also for rats. True, rats fell ill and died more slowly than birds. The most interesting and, perhaps, unexpected thing was discovered during the autopsy of dead animals. All of them had damaged livers. Bernard Glemser writes about this: “Six months after starting feeding with purified food mixed with 20% Brazilian groundnut flour, nine out of eleven rats developed multiple liver tumors, and in two animals it metastasized to the lungs. Therefore, this food is carcinogenic. We believe these preliminary results are of general interest."

What does "general interest" mean? Of course, interest for science, importance for poultry farming, but also for humans. After all, groundnuts are eaten sprinkled with salt or sugar; nut oil is obtained from groundnuts, which is used in the production of margarine, added to other vegetable edible oils, etc. All this is explained by the high calorie content of groundnuts. One kilogram of groundnuts has the same calories as one kilogram of ham. The groundnut kernel contains dietary protein. If we add to this that groundnuts contain a complex of B vitamins, the large scale of consumption of groundnuts in a number of countries and at the same time the threat of... liver cancer will become clear!

The attention of scientists has also been drawn to the disease of Canadian trout with liver tumors. It turned out that in industrial cages in America, fish were fed dry food made from cottonseed, but this was apparently also poisoned with aflatoxin. Further research and observations revealed that pheasants, pigeons, and chickens are sensitive to aflatoxins. Among mammals: pregnant sows and piglets, calves. In cows under experimental conditions, aflatoxins were found in milk, although aflatoxin was not found in commercial milk.

All the facts and discoveries made it possible to consider aflatoxin a carcinogenic substance. And from here important conclusions are drawn about the prevention of disease in humans. Searches in this direction continue. They are extremely important, because in nature there are a huge number of molds - tens and even hundreds of thousands of species. Not all of them, of course, are harmful; on the contrary, many of them are very useful, producing valuable therapeutic drugs, such as antibiotics. The challenge is to use the beneficial properties of molds to understand their harmful roles. Understanding means studying a huge number of molds, identifying conditions in nature, for example, humidity or dryness of the climate and other factors that influence the formation of aflatoxins. What plants and grains can be poisoned by mold fungi? Drying, for example, deprives mold fungi of favorable conditions for their life and, consequently, the production of aflatoxins. Step by step, the study of aflatoxins continues so that, knowing the enemy, we can fight and defeat him.

From the above it is clear how diverse the factors are associated with the occurrence of tumors. What about viruses?

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There is no single cause of cancer. In fact, there are a huge number of them. Every day, thousands of people around the world learn about their new and dangerous enemy – cancer. According to statistics, by 2020 we can expect the number of cancer patients to double – from 10 million to 20 million.

All over the world, groups of scientists are making multiple attempts to study the mystery of the origin of cancer and, to be honest, thanks to their hard work, progress in the study of this problem has reached incredible heights.

Already, there are many different assumptions and hypotheses explaining the causes of cancer, but they all agree on one thing - in some cases they arise through the fault of the patient himself.

Main causes of cancer:

  • Poor nutrition
  • Obesity, sedentary lifestyle
  • Smoking, drug use, alcohol use
  • External factors - exposure to radiation, industrial emissions
  • Heredity
  • Viruses
  • Depression
  • Weakening of the immune system

Food carcinogens

The human body is ultimately formed from what it eats. Statistics show that in more than a third of cases, the causes of cancer are associated with poor diet. Therefore, scientists cite exposure to carcinogens that enter the human body in food as a possible cause of cancer.

Many of the foods we are familiar with contain substances that, if consumed unbalanced or excessively, can lead to illness. These primarily include simple carbohydrates and trans fats. Research shows that overcooked foods contain a lot of carcinogens. Therefore, the best way to prepare food is boiling or baking. There is also evidence that food that contains an excess of proteins (more than 20%) contributes to the development of the disease. Therefore, you should follow a balanced diet with enough plant foods - vegetables and fruits.

However, plant products are also not always safe in terms of carcinogenicity, since they often contain nitrates and nitrites. Another proven food carcinogen is benzopyrene, which is found in smoked products. Therefore, it is recommended to exclude such products from the diet or reduce their consumption to a minimum.

It should be noted that not all substances that are considered dangerous in terms of carcinogenicity are actually so. For example, there is no scientifically proven data on the carcinogenic properties of GMO foods. The same can be said about monosodium glutamate, which is widely used in oriental cuisine. However, monosodium glutamate, as an extremely strong seasoning, is often used to hide from the consumer many substances that are truly harmful to health, including carcinogens.

Genetic predisposition

The causes of cancer are not always associated with an unhealthy lifestyle. Scientists attribute hereditary or congenital predisposition, as well as various mutations, to the second reason why the development of cancer is possible. No matter how much one would like it, every person who is not at risk of developing cancer has a 20% chance of developing one or another tumor. And for those who are at risk, this probability may be significantly higher. However, one should not exaggerate the influence of genetic predisposition, because, as statistics show, it is responsible for the occurrence of only 10% of diseases.

Viruses

Over the entire history of cancer, many cases have been identified in which ordinary viruses were the cause of cancer. Thus, it was found that infection with the papilloma virus can cause; people infected with T-lymphotropic virus may be susceptible to developing a rare and aggressive form of leukemia; the development of primary (developing in liver cells) liver cancer may be associated with infection with chronic hepatitis of various forms (B, C). Some viruses can cause stomach cancer. In general, viruses are responsible for approximately one in ten cases of cancer.

Bad habits - alcohol and smoking

Numerous studies show that cancer and tobacco smoking have a clearly established connection. This primarily concerns lung cancer, but not only that. A smoker has a high risk of developing tumors of the esophagus, pharynx and oral cavity and some other organs. Smoking is one of the most serious factors in terms of its contribution to cancer incidence. Approximately one in five cancer deaths is directly related to tobacco use. Moreover, not only smokers are in danger, but also those who are close to them and are forced to inhale tobacco smoke. Excessive alcohol intake is also a common cause of cancer. Strong drinks put the body at increased risk of problems with the liver and digestive organs.

Negative environmental influences

Cancer also has a cause such as exposure to carcinogens from the environment. Oncogenic factors include many chemicals that can be found in modern civilization and exposure to radiation. Substances that are unsafe in this regard surround us everywhere. These include many household chemical products, asbestos, and some plastics. There are also many carcinogens in car exhaust gases. Industrial pollution containing benzene, formaldehyde, and dioxins add their contribution to the list of carcinogenic threats.

As for radiation, many believe that only nuclear power plants pose a danger. However, in reality this is not the case. Radiation surrounds us everywhere, because even the walls of houses contain radioactive substances. Solar radiation, which contains ultraviolet rays that can negatively affect the skin, is also dangerous. It should be mentioned that many people are afraid of medical examinations using x-rays, but in fact the dose of radiation received from them (if not carried out daily) is extremely small and cannot be a serious risk factor.

Depression

It is also worth mentioning the connection between mental state and the development of cancer. By now, most scientists agree that stress and prolonged depression can cause cancer. Stress does not directly affect tumor formation, but in excessive quantities it can significantly suppress the immune system, which can undermine antitumor protection.

The thing is that under stress, the endocrine glands release hormones that can suppress the defense of the immune system. In particular, stress affects cells of the immune system such as neutrophils and macrophages - specialized defenders of our body from tumor formations. That is why in case of cancer it is necessary to control and not succumb to various circumstances that can provoke another attack of stress.

In the modern world, it has become quite difficult to avoid such a serious disease as cancer. According to statistics, by 2020 the increase in mortality from cancer will double - from 6 million to 12 million. We hope that after reading and learning the main causes of cancer, you will take care of your own health and the health of those around you - This, of course, will not get rid of the disease, but you can reduce the likelihood of its development.

A cancerous tumor is an uncontrolled growth of tissue under the influence of external factors that negatively affect the DNA of cells and cause gene mutations. As a result of pathological changes in the DNA structure of cells, cancerous tissue grows in the body, forming a malignant tumor. can be stopped both surgically and by other methods related to both irradiation of the tumor and the use of medications.

Features of tumor development

At their core, tumors can be benign or malignant.

A benign tumor is a proliferation of cells of the same tissue within which the tumor grows. A benign tumor grows slowly only within one focus, squeezing and constricting the healthy tissue of the damaged organ. Externally, the tumor differs little from healthy cells and does not metastasize, which means that after its removal (by surgery), the patient can get back on his feet within a few days. The likelihood of relapse is minimal.

A malignant tumor (cancer) grows very quickly, penetrating the tissues adjacent to the lesion, damaging their structure. It can spread throughout the body through blood and lymphatic vessels, which is why surgical removal does not guarantee a complete recovery, since tumors can reappear in a new focus.

Stages of tumor development

It is known that in the human body there are millions of cells with genetically altered DNA, but the immune system and other protective mechanisms prevent the development of cancer cells. Development of a cancerous tumor It begins with the fact that, under the influence of one or two external factors, the immune system ceases to restrain cell mutation, and it begins to grow and divide. The following stages of tumor development can be distinguished:

  • Initiation:

Under the influence of the environment, a change occurs in the genome of the cell. It is almost impossible to identify this stage in order to begin timely treatment.

  • Promotion:

At this stage, the number of mutating cells with an altered genome increases. This stage can be called precancerous, since the reaction of changes in the genome is reversible. Such changes in the tissue of the affected organ can be detected with regular, thorough preventive examinations.

  • Progression:

The stage is characterized by the active growth of cells with an altered gene, in aggregate, which are a tumor in the sense that is used in diagnosis.

  • Metastasis:

The process of tumor development in neighboring tissues and organs. Removing a cancerous tumor does not guarantee the patient a complete recovery. Clinical studies have shown that at the time of surgery it is not always possible to determine whether the process of metastasis has begun. Therefore, at this stage, cancer patients need not only anti-cancer therapy, but also constant medical examination at least once every three months for 2-3 years.

Reasons for tumor development

The causes of tumor development are very diverse. Conventionally, risk factors for tumor development can be divided into three groups:

  1. Physical (ultraviolet, radiation).
  2. Chemical (effects of various types of carcinogens on tissue cells).
  3. Biological (mutation of cells under the influence of viruses).

Among the most common risk factors for developing a malignant tumor are the following:

  • Smoking. In 30% of cancer cases, it is the influence of tobacco that causes tumors of the respiratory system - from beginning to end.
  • Poor nutrition. An equally common cause of mutations at the genetic level. Poor nutrition and the use of products containing carcinogenic substances that can affect the structure of DNA can become a trigger, starting the mechanism of tumor development.
  • Heredity. Predisposition to cancer can be transmitted at the genetic level.
  • Ultraviolet radiation, polluted atmosphere, sedentary lifestyle - only in 5% of cases can be factors.
  • Various viruses and .

As you can see, the main reason why tumor development, is a wrong lifestyle. Under the influence of air poisoning substances, as well as when using in the diet products grown with the use of chemicals, drinking alcohol and tobacco, cells prone to mutation begin to multiply, and a weakened immune system is unable to stop this process.

Cancer is not a death sentence. In order to avoid it, it is necessary to minimize the influence of risk factors, as well as periodically undergo a medical examination.

Not everything is known about the causes of the tumor. The predisposition to cancer of a particular organ (for example, breast, stomach) is inherited, i.e. is of a family nature. Strictly speaking, hormonal abnormalities in the body or local structural disorders in any organ (intestinal polyposis, birthmarks on the skin, etc.) are inherited. These deviations and irregularities can lead to the development of a tumor, which was noted more than a hundred years ago by the German pathologist Yu.F. Congame.

However, for the occurrence of a tumor - oncogenesis - tissue deformities alone are not enough. Mutagenic stimuli are required to cause changes in the hereditary apparatus of the cell and then tumor transformation.

Such stimuli can be internal or external - physical, chemical, viral nature, etc. Internal, for example, increased production of hormones or other metabolic products, their imbalance. And external ones are physical, for example, ionizing or ultraviolet radiation. These factors have a mutagenic and, therefore, carcinogenic effect, which triggers a mechanism that produces cancer cells in ever-increasing numbers.

It is assumed that any cell has a tumor growth program. This program is written in special genes - oncogenes. Under normal conditions, oncogenes are strictly blocked (repressed), but under the influence of mutagens the blockade can be lifted, and oncogenes are able to work.

It is also known that many carcinogens suppress the body's immune system, freeing abnormal cells from its strict and constant control. The control and restorative functions of the immune system sharply weaken in old age, when a malignant tumor most often appears. But in addition to heredity, cancer can be acquired, for example, consider:

Stomach cancer. In general, stomach cancer depends on a number of reasons. For example, eating pork is more dangerous than eating lamb or beef. The risk of developing stomach cancer is 2.5 times higher for those who consume animal oil every day. There is also a lot of starch (bread, potatoes, flour products) and not enough animal proteins, milk, fresh vegetables and fruits. The incidence may even depend on the nature of the soil. Where there is a lot of molybdenum, copper, cobalt and little zinc and manganese in the soil, as, for example, in Karelia, stomach cancer is much more common.

Mammary cancer provoke sex hormones (estrogens). More than a century of experience in studying this type of cancer has allowed scientists to draw clear conclusions: the later a woman has her first child, the higher the risk of breast cancer.

The likelihood of getting sick, for example, increases three times if the first birth occurred at 30 rather than at 18 years old. Recently, another interesting hypothesis has emerged about the benefits of early pregnancy. It turns out that the fetus produces a protein called alpha-fetoprotein. Some of this protein “leaks” into the mother’s blood, protecting against malignant diseases. It must be said that there are substances in the environment that affect the incidence of breast cancer. For example, tobacco smoke contains almost exact copies of estrogens. And they act accordingly - they provoke cancer. But some plants contain compounds (flavonoids) that protect us from cancer. They are found in tea, rice, soybeans, apples, cabbage, salads, and onions. It is with the regular consumption of some of these foods that scientists associate the low incidence of breast cancer in the East.

Pancreas cancer. Scientists believe this is due to increased consumption of animal proteins and meat.

Bladder cancer, according to doctors, depends largely on the person’s large amount of smoking.

Cervical cancer directly related to sex life. Even in the last century, it was noticed that, as a rule, married women die from cervical cancer, while virgins and nuns are spared the trouble. Later they found an explanation for this fact - not entirely obvious, however. It turned out that this female disease depends... on the man. More precisely, on how concerned he is with the hygiene of his genitals.

Prostate cancer Today it occupies one of the first places among male oncology. There is every reason to believe that the cause of prostate cancer is living conditions and habits. For example, a commitment to red meat and animal fats. It is believed that animal fat increases the level of sex hormones in the blood and thereby provokes the disease. Including vegetable oil and fish oil in your diet reduces the chance of getting sick.

Testicular cancer- a relatively rare tumor. It mainly affects white men. The reason is simple - low life expectancy.

But what about alcohol, doesn’t it have consequences? Excessive consumption of alcoholic beverages is one of the significant causes of cancer in some areas. French scientists from the International Agency for Research on Cancer reviewed scientific studies to establish the relationship between alcohol intake and the risk of developing cancer.

Scientists have found that excessive alcohol consumption increases the risk of developing cancers of the mouth, larynx, esophagus, liver, intestines and breasts, and is also likely associated with pancreatic and lung cancers. “Alcohol is underestimated as a cause of cancer in many countries around the world,” says study author Paolo Boffetta.

Alcohol intake is responsible for many cases of cancer, with a clear upward trend in the incidence of cancer in a number of countries, particularly in East Asia and Eastern Europe. Scientists believe that the risk of developing cancer is directly related to the amount of alcohol consumed. As the volume of hard liquor increases, the risk of cancer increases. However, the researchers are not calling for complete abstinence from alcohol. When consumed in moderation, researchers say the cardiovascular benefits may outweigh the possible harm. According to the latest recommendations of European experts, men can drink up to two and women up to one glass of wine per day.

In 2000, in developed countries, WHO estimates that alcohol consumption was associated with 185,000 deaths in men and 142,000 deaths in women, but prevented 71,000 deaths in men and 277,000 deaths in women.

The human body has amazing resilience. Not every smoker dies of cancer. But there will definitely be a weak point, and smoking will make a hole in your health. Nature has created us to be very strong, and many smokers, especially young ones, do not feel there is any danger to their health. But if you take a closer look! Dad is often irritated and often has a headache. Or maybe he smokes?

Healthy parents gave birth to a weak, often ill child. Or maybe one of his parents smokes? The baby was tormented by allergies. Or maybe his mother smoked during pregnancy or breastfed him? Are you having trouble sleeping? Poor memory? Look around you, maybe. Is there a smoker living near you? Thus, smoking goes along with alcohol. Scientists from the USA have found that women who smoke are more susceptible to colon cancer than men.

The observation results were presented at the 70th Scientific Meeting of the American College of Gastroenterology. During the study, doctors from Evanston, Illinois, studied the effects of alcohol and tobacco on the development of colon cancer in men and women using case histories.

It turned out that with the simultaneous use of both alcoholic beverages and tobacco, it was smoking that had a negative effect on the body of women, making them more susceptible to this disease than men.

Thus, we can conclude that there are many causes of the disease:

Smoking: greatly increases the likelihood of cancer of the lung, larynx, and esophagus.

Alcohol consumption: Can lead to liver and esophageal cancer.

Cases of malignant diseases in blood relatives.

Exposure to carcinogenic substances (asbestos, formaldehyde and others) and radioactive radiation.

In addition, bacteria and viruses contribute to the occurrence of malignant tumors.

The sexually transmitted human papillomavirus increases the risk of developing cervical cancer.

Helicobacter pylori increases the risk of stomach cancer.

Hepatitis B and C viruses can cause liver cancer.

And many other reasons for the development of malignant tumors.

Hypotheses for the causes of cancer.

There is no single generally accepted theory explaining the causes of cancer. The main ones are: chemical and viral.

Proponents of the chemical hypothesis associate the cause of cancer with exposure to chemicals (carcinogenic substances) on the body, which are known in large quantities. In favor of the chemical hypothesis, there are facts of the occurrence of cancer due to certain occupational hazards, for example, when working with paraffin, pitch, certain types of mineral oils, aniline derivatives and others.

Despite the fact that chemical theory is based on a large number of experiments carried out with various carcinogenic substances, with the help of which it is possible to cause cancer in animals, much in this teaching still remains unclear, controversial, and the etiological role of carcinogenic substances as the causes of all malignant tumors is not can be considered proven.

According to the viral hypothesis, cancer is caused by a specific filterable virus, which, by infecting the body's cells, ultimately leads to their malignant development. The viral nature of some malignant tumors in animals has been proven. However, it remains undoubted that cancer in experimental animals can be caused by carcinogenic chemicals, without the participation of a virus. In addition, filtrates from most mammalian tumors do not cause tumors to appear when inoculated into healthy animals, and therefore supporters of the viral theory have to make the assumption that the virus in such tumors is in an undetected state.

Since, according to supporters of the viral cancer hypothesis, chemical carcinogenic substances only prepare tissues for infection by a filterable virus, it is necessary to assume the widespread prevalence of the cancer virus in the body, because when exposed to carcinogenic substances, a tumor can arise in any part of the animal’s body. Nothing is yet known about the time and methods of infection of the body by tumor viruses, as well as the location of the viruses before the onset of cancer.

Most oncologists are of the opinion that the cause of cancer can be various environmental factors affecting the body, not excluding chemical and viral influences. However, whatever this effect may be, it must be long-lasting: Cancer does not arise suddenly; its development is preceded by a number of pathological processes that occur chronically, against the background of which, under certain conditions, malignant tumors can arise.

It follows that there are two main theories of the occurrence of cancer - chemical and viral.

Oncological diseases occupy the first positions among the causes of death. Their number is growing every year. This happens because diagnostic methods are improving or the number of cases is increasing.

Scientists around the world are trying to figure out why cancer develops. For some of its forms, the influence of certain factors has been established with great certainty.

Body cells divide when a tissue defect occurs or other cells die. But under the influence of various factors, some of them acquire the ability to divide uncontrollably and pass this property on to daughter clones. This is how cancer arises, which, when it enters the bloodstream or lymphatic channel, spreads throughout the body in the form of metastases.

What protects the body from malignant cells

Cancer cell

Resistance to cancer development is provided by three main mechanisms:

  • anti-carcinogenic;
  • anti-transformation;
  • anticellular.

The first type of protection against carcinogens is provided by the liver and immune system. When passing through the liver, hazardous substances are neutralized by oxidation by the microsomal system or by binding to the protein albumin.

This way they are transferred to an inactive form and cannot harm. Carcinogens are excreted by bile using feces or urine.

Vitamins E, A, C are involved in antioxidant protection, ensure the integrity and restoration of cell membranes damaged by chemicals or physical factors.

The immune system produces antibodies and interferon proteins to the corresponding carcinogens and oncogenic viruses.

Anti-transformation mechanisms prevent normal cells from turning into cancer cells. This is achieved in various ways:

  1. If defective DNA is formed during nuclear division, enzymes are launched that try to repair the damaged area. If it is impossible to replace the site, the p53 protein gene is activated, which triggers apoptosis.
  2. Allogeneic inhibition– synthesis by neighboring cells of certain substances that inhibit the development of tumor clones.
  3. Contact braking– entry of cAMP from a normal cell into a tumor cell, which suppresses proliferation.

Anticellular mechanisms are carried out by cells of the immune system. Transformed cells are detected by T lymphocytes. They act directly, damaging pathological clones, or indirectly through the release of various cytotoxic substances. After attacking the lymphocytes, the proliferates are destroyed by the macrophage system.

Specific antibodies include tumor necrosis factor alpha and beta. The action is that they increase the formation of oxygen and peroxide compounds by macrophages and neutrophils, lead to thrombosis in the tumor focus, after which tissue necrosis develops, stimulates the formation of interleukins and interferon.

Lymphocytes attack a malignant cell

But the tumor is capable of changing its antigenic structure, releasing substances that suppress the activity of lymphocytes, the receptors with which antibodies are able to interact are located inaccessibly. This is how evasion of the immune response occurs.

10 destructive factors

For some types of oncology, the reason that provokes their development has been established with high probability. But to a greater extent, various factors create the prerequisites for the development of a tumor against the background of a decrease in anti-carcinogenic protection.

Stress and hormonal levels

Israeli scientists conducted studies in which they found that Severe stress increases the likelihood of developing a tumor by 60%. The mechanism is explained by tension in the hormonal system, exhaustion of the adrenal glands, which actively secrete glucocorticoids during emotional stress.

Prednisolone is involved in providing anticancer protection, and reducing its level weakens this barrier.

The hormonal background consists of hormones with pro-oncogenic and anti-oncogenic effects. Estrogens stimulate the proliferation of cells of the endometrium, ovaries, and mammary glands that are sensitive to it, and increase the likelihood of developing oncology. If, in contrast to them, an insufficient amount of gestagens is synthesized, there is a high probability of developing hyperplastic processes.

Low immunity

A state of reduced immune defense is insufficient activity of cells from the group of T and B lymphocytes, decreased synthesis of immune proteins. This condition can develop after a serious infectious disease, when the immune system is under tension for a long time and its reserves are gradually depleted.

Exhaustion and liver disease are often accompanied by a decrease in the amount of synthesized protein, which is necessary for the synthesis of interferon and immunoglobulins. This means that there will be a deficiency of the humoral immune system.

Autoimmune diseases are characterized by a distortion of the defense system and its direction against one’s own cells. In this situation, the tumor develops due to an incorrect reaction to various antigens, the escape of cancer cells from the immune system.

Another proof of the influence of the immune system on cancer pathology is SID-associated tumors. More often these are Kaposi's sarcoma, lymphoma, and invasive cervical cancer. A decrease in the number of lymphocytes leads to uncontrolled division of altered proliferates and the development of carcinoma.

Chronic diseases

In organs affected by chronic diseases, cells suffer from hypoxia and are damaged by various inflammatory factors. Against this background, proliferation processes intensify, which are aimed at replacing damaged areas.

But inflammation also leads to damage to the stem cells from which young ones are formed. Against the background of decreased immunity, which is observed in many chronic diseases, anticancer protection is weakened, altered cells divide and form pathological foci.

Some diseases directly affect the likelihood of developing cancer. Viral hepatitis is accompanied by active proliferation, which increases the percentage of liver carcinoma development. Chronic intestinal diseases and inflammation of the cervix caused by direct damage by the human papillomavirus reliably lead to the development of a tumor.

Ecology

Pollution of the external environment with toxic emissions, radiation, air smoke in large cities and near industrial enterprises directly affects cell damage.

It has been proven that after the accident at the Chernobyl nuclear power plant, the incidence of thyroid cancer increased significantly. In this case, this is explained by the ingress of radioactive iodine into drinking water and food. From there it entered the thyroid cells and irradiation and damage occurred from the inside.

Poor nutrition

WHO has identified malnutrition, lack of fruits and vegetables in the diet, and low body weight as the top five causes that lead to the development of cancer. This is explained by an imbalance of nutrients, a decrease in protein synthesis and a delay in metabolic products in the body.

Lack of physical activity

Sufficient physical activity keeps the entire body in good shape and stimulates intestinal function. This means that there is no retention of toxic substances and their negative impact on its walls. After physical exercise, blood flow increases, blood oxygen saturation increases, hypoxia decreases - its damaging effects on cells are eliminated.

UV rays

Solar radiation is considered a natural carcinogen. It has the greatest impact on the development of skin cancer on representatives of the Caucasian and Mongoloid races, as well as albinos.

The anti-carcinogen in this case is melanin, which gives the skin a dark tint.

Tanning is a form of skin burn, so proliferation processes are enhanced, but sometimes the protective mechanisms are not enough and cancer develops. If you intentionally tan, the risk increases 4-5 times. Sunbathing in solariums is not an alternative; the possibility of getting skin cancer remains.

Heredity

Predisposition to various diseases can be identified in most people. But the likelihood of developing cancer increases with chromosomal pathologies: Down syndrome - leukemia, Shereshevsky-Turner syndrome - uterine cancer, Schweer syndrome - ovarian cancer.

There is a phenomenon called “cancer families” by Warthin. They are characterized by the occurrence of malignant tumors in 40% of relatives. Their age of development is significantly lower than the average for this type of tumor. Often they are not limited to one neoplasm.

The reason lies in genetic rearrangements, which are firmly fixed in the chromosomes and are implemented over generations under the influence of provoking factors.

Alcohol

Directly strong alcohol and alcoholic beverages are not direct carcinogens. But with systematic use, the likelihood of developing cancer of the esophagus and stomach increases. Alcohol has a damaging effect on the epithelium, proliferation increases and the preconditions for the development of carcinoma are created.

Smoking

Tobacco smoke is rich in various carcinogens:

  • arsenic compounds;
  • nitrosamines;
  • radioactive substances (polonium and radon);
  • 2-naphthynamyl.

The incidence of lung cancer in smokers increases many times over compared to non-smokers. Even passive smoking is a risk factor.

Carcinogens act not only when smoke is inhaled, but also when they enter the bloodstream. They spread throughout the body and affect tissues that are related to them. This explains the increase in carcinoma of other sites in smokers.

Additional questionable factors

Many other causes of cancer are actively discussed, but most of them are not confirmed by research. Using a microwave for cooking does not result in additional radiation exposure. Cell phones and signal towers have no more impact on brain cancer than other emitting devices - power lines, computers, televisions.

Bottom line

It is not always possible to determine the exact cause of the disease. It is difficult to determine at what stage the mechanisms of damage began to prevail over protection. For most cancer processes, there is a combination of various factors.

For example, against the background of chronic diseases, a person began to eat worse, body weight and immunity decreased. In a state of prolonged stress, the hormonal levels changed, the person resorted to alcohol as a remedy for depression, which led to alcoholic liver damage and hepatitis.

And there can be a lot of such combinations. Therefore, at this level of science, the cause of the tumor is established tentatively.

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