Affiliation: Departamento de Biologia Celular e Molecular (FABIO) and Instituto de Pesquisas Biomedicas,PUCRS, Av. Ipiranga, 6690 2° andar, 90610-000 Porto Alegre, RS, Brazil.
Although a great body of evidence is available on the immunosuppressive strategies employed by tumors in order to grow, cancer patients are not considered immunosuppressed individuals. Chemotherapy used in different cancer treatments frequently leads to leucopenia and affects immune responses. Tumors of the immune system can also cause immune alterations, due to their very nature. However, in the absence of preventive routine exams, patients can bear tumors for rather long periods of time without any specific indication, not being particularly prone to contracting infectious diseases compared to cancer free individuals. In this review, we analyze the existing data on the effects of tumors on the immune system of cancer patients. An interesting pattern emerges, suggesting that immunosuppression exerted by tumors is mainly local, rather than systemic. However, some alterations in DCs of cancer patients have been recently described, indicating the interactions between tumor and immune cells may be more complex than previously imagined. This has important implications of the design of anti-tumor therapies as well as in patient quality of life.