Peritoneal carcinomatosis is viewed by many experts as a terminal illness with an unfavourable course and prognosis. Existing therapies are controversial and exhibit ambiguous efficacy. We review the current state of the art in therapy for peritoneal metastases of various origin and its historical background. Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy compound the treatment of choice as achieving the highest survival rates. Palliative surgery and systemic chemotherapy are an alternative that proved even more aggressive and ineffective in comparative survival evaluations. Manifold studies and expert opinions exist on the efficacy and expedience of cytoreductive surgery and hyperthermic intraperitoneal chemotherapy in treatment of peritoneal carcinomatosis. Today, however, their routine use in everyday practice is hotly debated. Despite an evident progress in managing peritoneal metastases, a series of questions remain unsolved. Contentious research data, late diagnosis, low treatment efficacy in severe peritoneal dissemination, a limited applicability of cytoreductive surgery and hyperthermic intraperitoneal chemotherapy, all highlight the importance of inventing and developing novel methods for early high-accuracy diagnosis and careful selection of the treatment strategy. Fundamental knowledge of malignant metastasis underlies the choice of patient management and the innovative toolkit for prevention and treatment of peritoneal carcinomatosis.

The greater omentum is an organ in which metastases of malignant neoplasms of the female reproductive system are often formed. The issues of adaptive and reactive transformations of the greater omentum under conditions of a tumor process in the organs of the female reproductive system have been insufficiently studied. The aim of the study was to elucidate morphological and functional ultrastructural and immune-histochemical changes in the greater omentum in women with ovarian tumor lesions. Using the methods of light and electron microscopy, immunohistochemistry and morphometry, the ovaries of 48 women were examined, who were diagnosed with poorly differentiated serous-papillary adenocarcinoma stage II (20 patients, group 1), stage III (28 patients, group 2). In stage III patients, numerous tumor metastases were detected in the greater omentum. The results of the study showed that in the patients of the 2nd group, in the peri-tumor areas of the greater omentum, the vessels of the microvasculature were dilated, in the connective tissue, moderate edema and leukocyte infiltration were observed. Immuno-histochemical markers showed an increase in the number of immunocompetent cells, mainly T-lymphocytes in the tumor and in the peri-tumor areas. In the tumor and in the surrounding areas of the greater omentum, the process of neoplasm of blood capillaries was noted, differences in the density of collagen fibrils in different parts of the serous membrane were revealed, and the presence of numerous holes was shown, the sizes of which were reduced in areas with metastases. The results obtained show the adaptive and reparative capabilities of the structures of the greater omentum during the tumor process in the organs of the female reproductive system, indicate the important role of the greater omentum in providing protective reactions in the abdominal cavity. In response to the invasion of tumor cells, the processes of angiogenesis are activated in the greater omentum, and the number of immunocompetent cells increases in neo-lymphogenesis. The materials of the study indicate a significant plasticity and reactivity of the greater omentum under conditions of a tumor process in the body. However, the presence of a pronounced proliferative activity of tumor cells in tumor metastases indicates that these adaptive capacities are insufficient to resist tumor invasion into the greater omentum.

Peritoneal metastasis occurs in a number of heterogeneous tumors originating from the ovaries, stomach, intestines, pancreas, lungs, breast, and melanoma. Peritoneal carcinomatosis significantly reduces overall survival. While being almost unresponsive to treatment, dissemination of tumor cells along the peritoneum aggravates the course of the disease. Despite the use of locoregional treatment, peritoneal carcinomatosis is still considered to be an aggravating factor with a poor prognosis. Peritoneal carcinomatosis cannot be defined as a separate locoregional process with its own biology and oncogenesis due to the lack of clear understanding the molecular and biological features of peritoneal metastasis, as well as generally recognized standards for diagnosis and treatment of malignant neoplasms with various localizations. Addressing peritoneal carcinomatosis as a separate developing molecular event will enhance the understanding of its morpho- and oncogenesis and strengthen the search for therapeutic, diagnostic and preventive approaches to its management. Th e paper presents a bibliographic study of publications on exploring peritoneal metastases from various sites, including the abdominal and pelvic organs. Th e known mechanisms of tumors metastasis to the peritoneum are characterized in the paper. Diagnostic approaches to peritoneal carcinomatosis were assessed and compared. Th e collected data analysis revealed the main gaps in the understanding of peritoneal carcinomatosis oncogenesis.