Tumor microenvironment and metabolic factors: contribution to gastric cancer.

Malignancy may be characterized as a state formed in the setting of specific tumor-host relationships at the molecular and cellular microenvironment levels. R.E. Kavetsky and his collaborators distinctly outlined the concept of tumor-host interaction. Tumor is a complicated biological system closely connected with the organism, where it arises and develops. Tumor cells are in the environment of different factors that form tumor microenvironment playing an active role in the disease progression. There are two types of tumor microenvironment: the metabolic microenvironment mediated by factors of tumor microphysiology (blood flow, vascular permeability, oxygenation, extracellular рН, interstitial fluid pressure, etc.) and the cellular-molecular microenvironment comprising interactions between tumor cells and non-tumor cells and the factors of the stromal compartment. Factors of tumor microphysio-logy can modify the interaction between tumor cells and surrounding non-tumor cells and molecular components and they form the tumor profile that influences the pressure of tumor on the host. The review presents the data concerning the role of metabolic microenvironment of tumor cells from the point of tumor-host interaction in order to employ these parameters to working out the methods of diagnosis and prognosis of disease outcome in patients with gastric cancer. Special attention has been paid to hypoxia as a key factor of metabolic microenvironment that positively affects tumor progression, stimulating its aggressiveness, metastasis and resistance to therapy and is regarded as a factor of unfavorable prognosis. It was shown that there is possible clinical relevance of tumor classification based on the level of tumor oxygenation that may be advantageous for selection of patients for individualized therapy that may give the hope for enhancement of treatment efficacy.