General conclusions on the etiology and pathogenesis of tumors

A number of reasons causing the tumor, known or at least clarified. These include first of all blastomogenic action of some chemical and physical agents. For the first time the causes of cancer have been established in cases of so-called occupational cancer. Cancer radiologists, skin cancer chimney sweeps, bladder cancer employees aniline dye plants were the first evidence blastomogenic some agents of the external environment on the person.
The cases of occupational cancer in the narrow sense is a tiny the share of the total number of tumors in humans.
Because the observations of occupational cancer and in numerous animal experiments firmly proven blastomogenic action radiation agents, one of the ways to study the etiology of tumors and develop their prevention is to study the level of radiation and the struggle for its decrease.
In the etiology of many human cancers are of great importance dishormonal factors. Numerous experimental data and clinical observations suggest that the main causes of various tumors uterus, ovaries, breast, testicular, prostate gland, adrenal, pituitary gland, thyroid gland, and maybe some other neoplasms are dishormonal violations. In these cases, preventive measures to prove more difficult than in cases exogenous carcinogenic agents. However, the elucidation of the etiology and those Acting opens the way to their prevention and efficient treatment.
The etiology of a large group of human cancers, including such common, such as stomach cancer, is still largely unclear. However, for many of these lesions is possible to think about the causes associated with disorders of metabolism in the body and in certain tissues, with violations of the process of growth and differentiation of tissues, regeneration and organogenesis.
Certain types and forms of cancer are different nosologic unit, a separate disease, which can have different causes and to which shall be applied different methods of treatment and prevention. However, underlying all of this group of diseases is a single pathological process.
The emergence of Acting over a long period explained by the theory rudimentary, associated with the name of Congame (J. Cohnheim). If this theory else can explain formal Genesis of some of the so-called dysontogenetic tumors, causal, cause their Genesis she can't explain it in any case. All the data of modern experimental Oncology, showing that any of O. you can call from the cells of an adult organism, and not of separate rudimentary, speak against the theory of Congame.
Some facts and observations, the underlying "theory of irritation" Virchow (R. Virchow)have value to the present time. However, current data does not fit this theory. So, one of its provisions was that the agent that causes tumors to be "annoying" tissue to cause them repeated damage, inflammation and regeneration. Meanwhile, the study of Genesis numerous dishormonal Acting like a man, and in the experiment shows that inflammation is not a necessary stage in the development of tumors that from inflammatory and regenerative its restructuring.
On the basis of a number of experimental Oncology observations and especially the study of filterable O. and some viral agents created the hypothesis of viral etiology O. (see Opujolevidnami viruses). So far, however, there is insufficient evidence of the possible role of exogenous viruses in the etiology of the Acting person. One of the important arguments against viral etiology O. remains that cancer is not contagious, and tumor growth is not an infectious process. Therefore, at present the viral theory etiology Acting as a universal theory, recognizing the causes of all neoplasms exogenous parasitic viruses - informireba, cannot be accepted.
Causes tumors can be varied. All researchers, with rare exceptions, share polietiologic the theory of the origin O. Very common idea that the basis of occurrence of O. lies the abrupt change in the nature of the mutation (the so-called somatic mutation). Still think all blastomogenic agents act as mutagens. However, the gradual development of Grilles of precancerous changes, the progression of tumors from "dependent" to completely offline difficult to explain one of somatic mutations in the same cell. The latest experimental data on the study blastomogenic radiation also not stacked in frameworks of representations about somatic mutations.
In the pathogenesis of tumors along with causing agents is very important, and sometimes decisive role play implement the factors depending on the organism as a whole. Well known is the role of the nutrition of the body, and with changes in supply and related changes of metabolism and tissue reactivity. The importance of heredity as a factor determining the potency of growth and differentiation of cells and tissues, as well as the progress and direction of exchange processes.
In the light of modern concepts of the unity or close relatives of those molecular biological units that define heredity, differentiation, and cell metabolism, it is necessary to think, that in the changes of this kind of tissue particles and lies the clue to the pathogenesis of cancer. It is possible that a decisive moment in the origin O. are changes to nucleic acids under the influence of carcinogenic agents. In the case blastomogenic effects of chemicals may have a connection to them or their metabolites with proteins, resulting in the separation of the system regulating normal growth and differentiation of cells. If blastomogenic impact of viruses can be assumed entering into a normal cell alien to it components, again causing changes in normal differentiation and cell multiplication. Finally, radiation agents directly damage the system, which depends on the growth and proliferation, differentiation, and heredity cells. Thus, a variety of already known etiological agents lead, despite various mechanisms of action, and to a common pathogenesis of tumor growth. Cm. also Carcinogenesis.