INNIDIATION (Greek metastasis movement) — process of transfer in an organism of various pathological material, to-rogo the secondary pathological centers — metastasises result. Distinguish M. with formation of metastatic abscesses at transfer of pathogenic microorganisms that the hl is observed. obr. at sepsis (see), and tumoral M. at transfer of tumor cells with development of metastasises of a tumor.
Most often the term is used in relation to tumoral process since innidiation is one of signs progressions of a tumor (see), characterizing a current, a wedge, a stage, operability and the forecast of malignant new growths.
Schematically in the course of M. usually distinguish three stages: 1) an invasion — penetration of tumor cells into vessels; 2) transport — transfer of tumor cells a blood flow (fig. 1), a lymph, cerebrospinal liquid and liquids in perigastriums; 3) implantation — engraftment of the postponed tumor cells, their proliferation and development of a secondary tumoral node.
The invasion is connected with the infiltrative and destructive growth of a tumor, at Krom walls of vessels of surrounding fabric collapse. The tumor cells growing into vessels then come off and fond of a blood flow or a lymph, are carried with it in other fabrics and bodies. The invasion is observed also in the tumor where tumor cells can directly adjoin to the blood washing and feeding a tumor and a lymph. At this stage M. degree of a zlokachestvennost of a tumor, a low differentiation of tumor cells and their ability to separation — the so-called disjunction facilitating a separation of separate cellular elements from the ground mass of a tumor has an important role.
The second stage M. is made by transfer of tumor cells on a blood flow — hematogenous M. or a lymph — lymphogenous M. Neredko M., especially in late stages of tumoral process, has the mixed limfogematogenny character; e.g., in some cases hematogenous metastasises can become lymphogenous M. Inogd's source the so-called implantation M. resulting from transfer of tumor cells from the center of defeat on the healthy surface of body adjoining to it, and perineural M. — meets at distribution of tumoral process on perineural spaces (fig. 2).
Hematogenous and lymphogenous M. develops according to the general patterns of an embolism and can be direct — in the direction of a blood flow or a lymph (e.g., at M. in regional limf, nodes)", retrograde — at transfer patol. material in the direction, the return to a natural blood flow or a lymph (e.g., at M. of a carcinoma of the stomach in ovaries, blockade regional limf, nodes metastasises of a tumor), and paradoxical (e.g., at transfer patol, material through a nezarashchenny oval window of an interatrial partition or defect in an interventricular partition).
Kliniko-anatomichesky data demonstrate that sarcomas, as a rule, extend in the hematogenous way, and the hl is characteristic of cancer. obr. the lymphogenous and lympho-hematogenous way of M. Chastot M. of sarcomas on circulatory system many authors is explained by a subtlety of vessels in these tumors, to-rye are quite often covered by tumor cells. The most frequent localization of metastasises of sarcomas are the lungs serving as a peculiar filter on Krom settle tumoral emboluses; metastasises of cancer first of all are located in regional limf, nodes, at the same time primary metastasises are localized usually in a certain group limf, nodes, napr, in submaxillary (submandibular, T.) — at cancer of an under lip, in axillary and subclavial — at a breast cancer, in hepatic — at a carcinoma of the stomach, etc. From new growths of abdominal organs tumor cells on a portal vein get into the livers (portal type M.), at the same time only tumor cells which passed a liver or arose from metastasises in a liver reach lungs. For the tumoral emboluses extending with blood on venas cava (caval type M.), primary filter are lungs. Cells of primary cancer of lung get into a big circle of blood circulation (pulmonary type M.) also settle in capillary system of this circle. Nek-ry patterns of M. of tumors, napr, in bone system are known: at a prostate cancer the sacrum, ileal bones, lumbar vertebrae are surprised more often, femurs, edges, humeral bones are more rare, at hypernephroid cancer of a kidney — humeral and femoral to Nosta, edges, shovels, bones of a skull, a backbone. Widespread M. is observed, e.g., at a melanoma and cancer of a lung; metastasises in a terminal cancer of a gullet and a body of the womb are rather seldom observed. In the course of M.
its third stage — implantation of tumor cells is important. In peripheral blood, napr, at a lab. animals, the Crimea tumors are experimentally imparted, often find tumor cells, but at the same time not in all cases there are metastasises. This results from the fact that for development of metastasises of insufficiently mechanical embolic elimination of tumor cells, and special conditions are necessary, among to-rykh crucial importance belongs, apparently, to weakening of cellular and humoral factors of immunity, and also such degree of a zlokachestvennost of a tumor and a stage of its progression, at to-rykh the tumor cells which came off the main node do not perish and form secondary metastatic nodes in places of elimination. About value immunol, factors at M. the observations of a number of researchers specifying that in multiple and large metastasises usually fabric is less differentiated testify, and in single metastasises increase in a differentiation of cells in comparison with fabric of primary tumoral node is noted.
Time necessary for M.'s approach can be various: sometimes metastasises appear very quickly, after emergence of primary tumoral node, in some cases metastasises can arise in 1 — 2 years, and sometimes the so-called latent or dozing metastasises are found in many years after radical operation, napr, concerning a breast cancer, a large intestine, etc. Before - and the postoperative radiation therapy, antineoplastic means, an immunotherapy and other methods applied at treatment of tumors in a number of cases promote decrease in frequency of M. or later emergence of metastasises. M. can sometimes be observed at a high-quality morfol, a picture of primary tumor, napr, at hondroma and nek-ry new growths of a thyroid gland. The m can be absent at tumors with cutting anaplaziya (see). It demonstrates that M. not always matches other signs of a progression of a tumor.
M.'s process is reproduced and studied in an experiment on a lab. animals, at the same time it is possible to create the special modifying conditions increasing its frequency, napr by means of mechanical, chemical or other damage of body, administration of nek-ry hormonal drugs, etc. Decrease in frequency of M. can be reached at artificial oppression of processes of a thrombogenesis that creates, apparently, the conditions interfering formation of a tumoral embolus from the tumor cells circulating in blood. Removal of a part of a tumor or a biopsy of experimental new growths, as a rule, does not increase the frequency of development of metastasises.
Diagnosis in a wedge, cases is quite often complicated. Sometimes the remote, especially single metastasises, napr, in a brain or a bone, clinically come to light earlier, than primary center (in particular, in lungs or a prostate gland) and incorrectly are accepted to independent primary tumor. Detailed clinical inspection of the patient and careful gistol, a research of biopsy material of a metastatic node (see. Biopsy ), and also dynamic observation help to establish the correct diagnosis. In M.'s recognition
are important rentgenol, and the tracer techniques of a research allowing to specify size, prevalence and the nature of growth of metastasises, their disintegration, suppuration, germination in the next bodies and fabrics give the chance to control efficiency of treatment.
Rentgenol, M.'s diagnosis is based on direct and indirect symptoms. A direct symptom of M. is direct display on roentgenograms single, several or multiple metastatic nodes of a tumor (fig. 3, and, b). At a big difference in absorption of x-ray emission in metastasises and surrounding fabrics (metastasises in lungs, bones, fatty tissue, and also all metastasises containing the centers of ossification and adjournment of salts of calcium) on survey roentgenograms, electroroentgenograms, tomograms tumoral small knots the size of St. 0,3 — 0,5 cm clearly are visible. At the small X-ray contrast (e.g., at M. in a brain or parenchymatous bodies) metastasises find by means of computer tomograms (see. Tomography computer ), techniques of artificial contrasting with administration of gas — pneumomediastinum (see), a pneumoperitoneum (see), etc., and also administrations of contrast mediums in vessels (see. Angiography , Limfografiya etc.). Plentiful blood supply of metastasises (e.g., sarcomas, horionepitelioma, a malignant insuloma, carcinoid, cancer of a thyroid gland, etc.) allows to receive their sharp image on angiograms. Metastasises of cancer of lung, gullet, stomach, a pancreas, gall bladder usually contain few vessels and are visible on angiograms most often as defects in a shadow of body.
Refer increase in a shadow of the struck body, roughness of its surface, shift of the next bodies to indirect rentgenol, M.'s symptoms, etc.
Radio isotope diagnosis of M. is based on registration of changes of normal distribution radio pharmaceutical drug (see) owing to its various absorption in a tumor and the fabrics surrounding it. Metastasises decide on a hypermetabolism of substances and plentiful blood supply as sites of the increased radioactivity or the so-called hot centers, napr, at selective accumulation of radionuclides of iodine in metastasises of a number of tumors of a thyroid gland. Methionine, marked selenium-75, and drugs of indium-111 are used for detection of metastasises of nek-ry tumors in soft tissues, drugs of gallium-67 — for identification struck limf, nodes at a lymphogranulomatosis, various complex compounds of technetium-99m — for diagnosis of bone metastasises (fig. 4).
Metastasises of many tumors poorly absorb radionuclides and are found in the studied body as sites of the lowered radioactivity (the cold centers). Sometimes metastasises meet, to-rye do not accumulate radio pharmaceuticals. Nek-ry not tumoral diseases (e.g., arthritises) usually are followed by the increased accumulation of radionuclides and can simulate M. at a radio isotope research.
Treatment is based on the general principles of treatment tumors (see). Apply radiation therapy (see), chemotherapy (see), at single metastasises in some cases perhaps operational treatment. Sometimes single metastasises of nek-ry new growths can spontaneously disappear, exceptional cases such are described at metastasises of a horionepitelioma of a uterus and hypernephroid cancer of a kidney.
Prevention is a part a wedge, prevention of tumors. Prevention of development of metastasises, especially implantation, in the course of treatment of tumors is promoted by careful respect for the principles of an ablastika at onkol, operations, performing preoperative and postoperative radiation therapy.
According to nek-ry authors, the span, during to-rogo occurs doubling of volume of metastasises, makes, e.g., in metastasises of a colon cancer from 34 to 210 days, an osteosarcoma from 19 to 72 days, Ewing's tumor — from 20 to 42 days, etc. that allows to plan rational terms of routine maintenances for identification of the hidden metastasises (e.g., after a radical mastectomy concerning a breast cancer preventive rentgenol. researches are conducted, as a rule, at an interval of 6 months).
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