According to experimental oncology,a tumor is the only disease that occurs equally in all representatives of the animal world. The etiology of tumors, like its pathogenesis, has not yet been fully understood by scientists, but at the moment there are 4 basic theories:
2. Physicochemical. The main role in tumor development is performed by chemical carcinogens (3,4-benzpyrene, TIR and TRI metabolites, aflatoxins, etc.), ionizing radiation.
3. Dysontogenetic: tumor processes arise due to incorrect laying of tissues in the embryonic period.
4. Mixed - denies monoetiology of the tumor.
Manifestations of tumors
Symptoms of oncological processes in the bodyis classified into local and general symptoms. Local signs are direct evidence of a tumor, but often appear later than the general ones, which are associated with the distant effect of the tumor on target organs or with malfunctions of the depressed immune system. Such symptoms are combined in the so-called. paraneoplastic syndromes. They are characterized by a lack of connection with the local effect of the tumor, resistance to ongoing therapy, development only in the presence of malignant neoplasm and disappear in radical treatment. This allows for differential diagnosis of PNS with independent systemic diseases.
Pathogenesis of PNS
Because paraneoplastic syndrome developson the basis of a functioning tumor or its metastasis, the pathogenesis of each syndrome is associated with a disruption in the metabolism or reactivity of the immune system. So, the majority of tumors are a kind of "traps" for nutrients (vitamins, glucose, amino acids, lipids), which causes the development of degeneration of many tissues and general cachexia. Also, the presence of identical antigens in atypical cells and healthy leads to a cross-immune response, due to which normal cells are malignant or malignant. And tumors that arise on the basis of endocrine cells produce an additional amount of hormones. In this case, paraneoplastic syndrome will arise on the basis of a protective decrease in receptor sensitivity to hormones and aggravation of metabolic disorders.
The most frequent tumors areneoplasms of endocrine tissues. In this regard, there is an endocrine paraneoplastic syndrome. Its manifestation consists of an increased concentration of the hormone in the blood and its preservation, even after resection of the gland producing it and a decrease in secretion when the tumor is removed.
Articular syndrome manifested ashypertrophic osteoarthropathy, carcinolide arthropathy, gouty arthritis, polyarthritis. This paraneoplastic syndrome usually precedes the diagnosis of the tumor and even contributes to an earlier detection of the malignant process.
Hematologic and neurological syndromes havethe most severe course and rapid death. They manifest themselves in changes in the quantitative and qualitative composition of blood and neuropathies leading to irreversible organic changes in tissues.</ p>