I always counsel my patients about the role of physical activity in recovery. Almost inevitably, they are surprised that I ask them not to run a marathon, or work out for hours at the gym. In fact, I suggest doing what our grandparents did: WALK! So why do I focus on physical activity? Even light exercise may reduce the risk of death from breast cancer. In the Nurses’ Health Study, the greatest benefit occurred among women who did the equivalent of walking 3 to 5 hours per week at an average pace. In fact, there was little evidence of a link between increased benefit and greater energy expenditure. In addition, several studies have associated physical activity (after a breast cancer diagnosis) with improved quality of life. (http://jama.jamanetwork.com/article.aspx?articleid=200955#REF-JOC50040-4)
Physical activity can also reduce the risk of getting breast cancer. An expert panel of the International Agency for Research on Cancer of the World Health Organization estimated a 20% to 40% decrease in the risk of developing breast cancer among the most physically active women, regardless of menopausal status, type, or intensity of activity. (www.ncbi.nlm.nih.gov/pubmed/12119660)
Physical activity has been linked to lower levels of circulating ovarian hormones, which may explain the association between physical activity and lower risk of breast cancer. Lower estrogen levels among physically active women with breast cancer could potentially improve survival, although we still need more data. However, irrespective of the amount of benefit in the breast cancer arena, why would you not want to lower your risk of other cancers, heart attack, stroke, diabetes, and maybe even dementia?