Immunological changes in the circulation of cancer patients in response to 10- and 30-min acute exercise

Tumor-infiltrating lymphocytes are associated with a more favorable prognosis for solid tumors. In mouse models, exercise has been shown to reduce tumor growth through enhanced immunosurveillance. Here, the aim was to study immune cell and cytokine mobilization in lymphoma and breast cancer patients in response to 10-min and 30-min exercise. Participants were 15 lymphoma patients aged 59 (SD 17) years and 39 breast cancer patients aged 57 (SD 10) years who had not yet started their cancer treatments. The patients performed either a 10-min or a 30-min exercise bout on a bicycle ergometer. Blood samples were drawn before, during, and after exercises to analyze immune cell mobilization and 27 cancer-specific cytokines. A 30-min acute exercise increased the numbers of circulating total leukocytes and lymphocytes, CD4 + T cells, T helper (Th) 17 cells, regulatory T cells, CD8 + T cells, CD4 − CD8 − T cells, and CD56 + natural killer (NK) cells in lymphoma patients. Exploratory comparisons between the 10- and 30-min exercise groups showed broadly similar patterns of immune cell mobilization in both cancer cohorts. However, the mobilization of CD4 + T cells and NK cells was greater during the 30-min exercise compared to the 10-min exercise in breast cancer patients. Further, the levels of Eotaxin and IP-10 increased more during the 30-min exercise than during the 10-min exercise in breast cancer patients. Because the 10- and 30-min exercise groups originated from separate clinical trials with differences in participant characteristics and exercise protocols, these findings should not be interpreted as effects of exercise duration alone. Acute exercise stimulates the mobilization of both anti-tumoral and pro-tumoral immune cells in lymphoma patients, but relatively few changes were observed in circulating cytokines in both patient groups. Further studies on the effects of exercise on the tumor microenvironment and tumor growth are needed in humans.