Exercise impact on immune regulation of cancer

The incidence of several types of cancer is reduced by regular physical activity. Several possible mechanisms have been cited as potential mediators of the beneficial effect of physical activity on cancer prevention, including immune regulation. The immune system plays an important role in controlling tumor development by resolving inflammation and by detecting and eliminating transformed cells via a variety of mechanisms including macrophage phagocytosis and/or cytotoxicity, NK cell function, and T cell cytokine production and/or cytotoxicity. The immune system can also play a role in tumor promotion. The current review focuses on the role of acute and chronic, moderate aerobic exercise on immune endpoints relevant to anti-tumor immunity, including macrophage, NK cell and T lymphocyte function. Both acute and chronic exercise have been shown to consistently enhance phagocytosis and anti-tumor activity of macrophages which may contribute to better immunosurveillance and protection from tumor progression. In contrast, there is heterogeneity in the literature regarding the role of acute and chronic exercise on NK cell and T cell function. There is a growing body of evidence to suggest that chronic exercise training enhances antigen-specific T cell proliferation and cytokine production, which may play a role in anti-tumor immunity. However, to date, no studies have explored the role of exercise in regulating the immune response to tumors. Future studies should focus on immune regulation in tumor-bearing hosts to gain a better understanding of the complex relationship between exercise, immune regulation and cancer control.