Exercise training may slow tumor growth and improve outcomes for females with breast cancer – especially those treated with immunotherapy drugs – by stimulating naturally occurring immune mechanisms, researchers at Massachusetts General Hospital (MGH) and Harvard Medical School (HMS) have found. Tumors in mouse models of human breast cancer grew more slowly in mice put through their paces in a structured aerobic exercise program than in sedentary mice, and the tumors in exercised mice exhibited an increased anti-tumor immune response. “The most exciting finding was that exercise training brought into tumors immune cells capable of killing cancer cells known as cytotoxic T lymphocytes (CD8+ T cells) and activated them. With more of these cells, tumors grew more slowly in mice that performed exercise training,” says co-corresponding author Dai Fukumura, MD, PhD, deputy director of the Edwin L. Steele Laboratories in the Department of Radiation Oncology at MGH.
