Cancer (this article is in Russian — Рак) is a malignant tumor of epithelial cells of the skin, mucous membranes of the stomach, intestines, respiratory tract, various glands, etc. In connection with the morphological features distinguish the various forms of cancer: squamous cell carcinoma (develops primarily on the skin and mucous membranes covered with squamous epithelium), adenocarcinoma, Scherr and others.
Cancer (Latin cancer, carcinoma, from the Greek karkinos — cancer, crab) — a malignant tumor from the epithelium, that is, from the tissue that covers the animal organism from the outside and lining it from the inside, as well as its forming glands. Therefore, cancer is a malignant tumor (tumor, blastoma) of the skin, digestive tract, respiratory and urinary tract, lungs, kidneys, liver, genitals and glands. The name given by the doctors of the middle ages, is associated with the appearance of a tumor resembling cancer or crab. Cancer accounts for the vast majority of all malignant human tumors, including many sarcomas, hematological malignancies, glial tissue, bone, and other tumors. In some countries, cancer is understood as any cancer.
The occurrence of cancer
The tumor occurs due to metabolic disorders in the cells and the weakening of the control of intracellular processes by the body. As a result of the acquisition of new qualities and partial independence from the regulatory systems of the body, young dividing cells lose the ability to differentiate — they do not acquire proper functions and do not form a normally working tissue. Not participating in the life[ru] of the body, such cells become unnecessary to him, unnecessary. The body tries to get rid of them with the help of immune reactions, which are not always effective. The excess of young, all the time multiplying, but not working cells, besides requiring an increasing amount of energy and food resources, leads to the fact that such cells attack their tissue or organ. These cells (they are called tumor) are introduced into the tissues of the body, infiltrate (see Infiltrate) and destroy them, capture blood and lymph vessels, which are distributed throughout the body — metastasize (see Metastasis).
Cause of cancer. Oncogenesis
About the reasons of occurrence of tumor is known not all. The predisposition to cancer of an organ (for example, breast, stomach) is inherited, that is, it is of a family nature. Inherited hormonal abnormalities in the body or local structural disorders in any organ (intestinal polyposis, birthmarks on the skin, etc.). These abnormalities and irregularities can lead to the development of the tumor, which was noted more than a hundred years ago by the German pathologist Julius Friedrich Conheim. However, for the emergence of tumor — oncogenesis — tissue deformities alone is not enough. Mutagenic stimuli causing changes in the hereditary apparatus of the cell and then tumor transformation are needed. Such incentives can be internal (e.g., increased production of hormones or other metabolic products, their imbalance) or external — physical (e.g., ionizing or ultraviolet radiation), chemical, viral, etc. These factors have mutagenic and thus carcinogenic exposure that triggers the mechanism that produces cancer cells in ever increasing numbers.
It is believed that any cell has a tumor growth program. This program is recorded in special genes — oncogenes. Under normal conditions, oncogenes are tightly blocked (repressed), but under the influence of mutagens, the blockade can be removed, and oncogenes are able to work. It is also known that many carcinogens suppress the immune system of the body, releasing from its rigid and constant control deviated cells. Control and restoring functions of the immune system sharply weaken in old age, when most often there is a malignant tumor.
Form of cancer
Cancer tissue is a very mobile and changeable formation. Its behavior depends on many factors, including the intensity of protective anticancer reactions, which the body is capable of in a particular case. The human immune system can partially or completely destroy the tumor. It can also block cancer cells at an early stage and prevent them from penetrating deep into the organ (non — invasive cancer, or “cancer in place” in situ”). In the name of the form of cancer are reflected: belonging to a particular organ (lung cancer, ovarian cancer, etc. e.), the type of epithelium, serving as a source of tumor (squamous cancer, glandular — adenocarcinoma, basal cell, etc.), the growth rate, histological equivalent of which is the degree of maturity of cancer tissue (cancer differentiated and undifferentiated), properties associated with the degree of maturity of the tumor and the effectiveness of immune reactions in it (cancer aggressive, stable, regressive).
Clinic, diagnosis, cancer prevention and treatment
Symptoms of cancer appear relatively late, when the tumor reaches a significant size and disrupts the function of the organ in which it grows. If the organ is hollow, its patency may be disturbed, there are pathological (inflammatory or other) discharge, bleeding is possible. The patient feels weak, loses weight, his body temperature rises, he feels pain, the rate of sedimentation of red blood cells increases.
The most important principle of cancer diagnosis is its timeliness, detection of the tumor at an early (preclinical) stage, when recovery occurs in 80-95% of patients. For this purpose, all known modern medicine methods are used: clinical, biochemical, immunological, radiological, ultrasound, endoscopic, cytological, histological with a biopsy. The effectiveness of their combined application is very high.
Prevention of cancer — is, first, its detection at an early stage in the mass survey of the population, which is referred to the group of high risk. For this purpose, chest x-rays of lungs, mammography, PAP smear of the cervix, etc. Another problem prevention — create for people the optimal conditions for the existence of a minimizing contamination of the environment with a decrease in the probability of contact of the body with carcinogenic factors, the General health of the population. Such measures can significantly reduce the incidence of malignant tumors.
Cancer treatment — surgical, as well as with the use of hormones, radiation therapy and chemotherapy. To increase the body’s defenses resort to the effects on the immune system. Different methods of treatment are often used in combination with each other-depending on the stage of the disease, the location of the tumor, its tissue affiliation and other factors. There are many good clinics to treat this disease. In Russia[ru], a good cancer center in Yekaterinburg, possible treatment in clinics in Germany, and others.
The incidence of cancer (epidemiology)
Cancer is a disease[ru] of the elderly. In the industrialized countries[ru] of the West it ranks second after cardiovascular disease in the list of causes of death[ru] and, despite the efforts of physicians, is not inferior to it for many decades in a row. There is even an increase in the incidence of cancer in these countries (from 1960 to 1980 — one and a half times), associated, as believed, with the aging of the population and the deterioration of environmental conditions in large cities. Six million dead (in 1996 — 6,3 million) — this is an annual tribute to the humanity of malignant tumors.
In some cases, the cancer recedes. Thus, the implementation of a social program to combat gastric cancer in Japan in a relatively short time led to a decrease in the incidence of almost twice. A significant reduction in the incidence of gastric cancer has also been observed in the United States[ru] and Europe. However, it is connected with non-medical factors. The” culprit ” of the partial victory over the tumor was a household refrigerator, which radically changed the traditional methods of preservation of food products by salting and Smoking.
Different peoples and different geographical areas spread different forms of cancer. Japan and Russia are “sick” with stomach cancer. In the United States, developed countries of Europe, as well as in major cities of Russia, lung cancer and breast cancer predominate (in Moscow in 1996 from all forms of cancer died 225 thousand people). This is the result of pollution of the environment with industrial waste, exhaust gases of cars, tobacco Smoking, and also not always justified refusal of breastfeeding of newborns[ru]. In Africa, the national disaster — liver cancer (small protein food), in Mongolia and Kazakhstan — esophageal cancer (scalding hot and fatty foods), in India and Central Asia — oral cancer (the habit of chewing betel). Americans ‘ addiction to easily digestible fiber-free foods (“fast food”) has led to growth in the country of colon and rectum cancer.
The change of place of residence is accompanied by a gradual decrease (in a generation) in the incidence of “native” cancer and the acquisition of a predisposition to cancer prevailing in the new country of residence. The prevalence of various forms of cancer is studied by analyzing the living conditions, habits and eating habits of the population, the mineral composition of the soil and water, the entire set of environmental conditions; special maps are compiled that reflect the number of diseases of various forms of cancer in specific settlements of a certain region.
The science of cancer is called — Oncology (from the Greek onkos — tumor and logos — word, doctrine) — medical and biological science, studying the theoretical, experimental and clinical aspects of oncogenesis in humans, animals, plants and developing methods of recognition, treatment and prevention of tumors.
Oncology was formed in the 20th century on the basis of the achievements of experimental medicine. In the experimental (starting with the works of Russian scientist Mstislav Alexandrovich Novinsky, 1876) and theoretical Oncology has developed 3 main areas: viral (French scientist Amadeus Borrell, 1903; American the pathologist and oncologist — Francis Rous, 1911), chemical (Japanese scientists, K. Yamagiwa and K. Ichikawa, 1915) and radiation (the French scientist and radiologist Antoine Lacassagne, 1932, and others) depending on the inducing agent. In the USSR[ru], Lev A. silber, a scientist, microbiologist and immunologist, created the viral genetic theory of tumors. The rapid development of clinical Oncology is associated with the achievements of surgery, radiology, chemotherapy and immunology.
