WEDNESDAY, May 9 (HealthDay News) -- Physical activity correlates with reduced all-cause and breast and colon cancer-specific mortality, according to a study published online May 8 in the Journal of the National Cancer Institute.
Rachel Ballard-Barbash, M.D., from the National Cancer Institute in Bethesda, Md., and colleagues conducted a systematic review and identified 45 articles relating to physical activity, cancer survival, and biomarkers potentially relevant to cancer survival.
Based on consistent evidence from 27 observational studies, the researchers found that physical activity correlated with reduced all-cause, breast cancer-specific, and colon cancer-specific mortality. For survivors of other cancers, there was insufficient evidence for an association between physical activity and mortality. Preliminary evidence from randomized controlled trials of exercise that included biomarker end points suggested that exercise induces beneficial changes in circulating levels of insulin and related pathways, inflammation, and possibly immunity.
"Future research directions identified include the need for more observational studies on additional types of cancer with larger sample sizes; the need to examine whether the association between physical activity and mortality varies by tumor, clinical, or risk factor characteristics; and the need for research on the biological mechanisms involved in the association between physical activity and survival after a cancer diagnosis," the authors write.