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Summary Various processes, taking place both in cells and in their environment, are linked to carcinogenesis. This paper aims at recalling the complex mechanisms of oncogenesis, with particular attention paid to responses of the immune system. In development of solid tumours, leukaemias and lymphomas several common stages can be noted. A neoplastic disease cannot be understood considering only phenomena of genetic mutations. Neoplastic cells are characterised by an extensive antigenic variability and resistance to apoptosis. The cells create around them a microenvironment which protects them from defensive activity of the host. In the paper we present the recognised mechanisms of anti-neoplastic defense as well as several elements allowing the solid tumours and leukaemias to escape from the immune surveillance. The generally accepted treatment of tumours aims at reducing numbers of tumour cells. Following resection of a tumour, radiotherapy or chemotherapy, the parallel or consecutive stage of treatment was found to involve an increase in number of clones of immune system cells. One of the ways in which the immune system can be activated involves autovaccination of the host with own neoplastic cells in an apoptosis. However, attempts of such a therapy frequently brought no expected results due to blocked activity of cytotoxic cells. Therefore, the subsequent stage in activation of the immune system should involve elimination of the tumor-mobilized blockade of the system. Attempts toward this aim include neutralization of the tumour-blocked cytotoxic properties of defensive cells, first of all T lymphocytes. The recognized mechanisms of blocking T cells activity in the PD-1/PD-L1 system or due to inhibition of activation by CTLA-4 molecule provided rationale for development of effective tumour immunotherapy approaches.

Summary Here we present the concept of making own patient’s anti-cancer treatment more efficient and starting at testing the efficacy of immunological system. The respective tests are suggested, with special attention devoted to tumour-induced microenvironmental changes. The tumour should be considered to represent a complex tissue in which the cancer cells communicate directly and indirectly with the surrounding cellular immunological surrounding and develope traits that promote their own survival. The results of tests allow to propose a rational, individually profiled treatment of a patient, especially directed to elimination of blocks inhibiting the immunological system due to effects of cancer cells. The elimination can be implemented using commercially available antibodies, targeted at the cell surface receptors for inhibitors of T lymphocytes (CTLA-4 and PD-1). Outcome of the therapy is slow to appear and the results used to be selective. Some patients gain long term improvement and respective predictive markers are now tested. It is assumed that the future anti-cancer therapy will be individually targeted, based on individual tests and an assistance of own immunological system of the cancer patient.