Abnormal growth of blood vessels in solid tumors creates areas of hypoxia, which, in turn makes the tumors more aggressive and resistant to therapy. Exercise has been shown to improve blood vessel growth and perfusion of normal tissues and may have the same effect in solid tumors, according to a study published March 16 in the JNCI: Journal of the National Cancer Institute.
To investigate the effect of exercise on tumor growth and response in breast cancer, Allison S. Betof, of the Duke Cancer Institute, Duke University Medical Center, Durham, NC, and Department of Internal Medicine, Massachusetts General Hospital, Boston, MA, and colleagues implanted breast cancer cells into mice and randomly assigned them to wheel-running or sedentary groups. They then assessed tumor growth, blood vessel density, maturity, and perfusion, extent of tumor hypoxia, and response to a chemotherapeutic agent.
The researchers found that after 18 days, compared to tumors in the sedentary group, those in the exercise group had slower growth and higher blood vessel density, maturity, and perfusion. Regions of hypoxia were 48.8% of tumor area in the sedentary mice but only 25.5% in the exercised mice. When exercise was combined with the chemotherapy drug cyclophosphamide, tumor growth was slower than in sedentary mice as well as in mice subjected to exercise alone or the drug alone.
However, the authors caution that more work is needed to determine the effects of exercise on slower-growing tumors and in combination with drugs or treatments targeting tumor blood vessel growth.
The authors conclude, "...our findings shed new insights into the potential anticancer role of exercise as either adjuvant therapy or a combination therapeutic strategy in patients with solid tumors."