The effects of physical activity on breast cancer survivors after diagnosis

Adverse health outcomes are often seen in breast cancer survivors due to prolonged treatment with side effects such as loss of energy and lack of physical strength. Physical activity (PA) has been proposed as an adequate intervention for women with breast cancer. Therefore, this review summarizes the effects of physical activity on breast cancer survivors after diagnosis. We searched electronic databases including PubMed, Medline, Embase, and Google Scholar for articles published between January 1980 and May 2013. We included a variety of studies such as randomized controlled trials, pilot studies, and clinical trials. We reviewed these studies for three major outcomes: changes in breast cancer mortality, physiological functions, and metabolic biomarkers. Of 127 studies, 33 studies were selected as eligible studies. These studies included physical activities of varying type, duration, frequency, and intensity (e.g., aerobic and resistance training) and examined changes in three major outcomes among breast cancer survivors. Many of the studies suggest that breast cancer survivors benefit from engaging in physical activity, but some studies were limited in their ability to provide adequate evidence due to relatively small sample sizes, short intervention periods, or high attrition. Based on epidemiological evidence, recent studies demonstrated that those breast cancer survivors who engaged in physical activity significantly lowered their risk of breast cancer mortality and improved their physiological and immune functions. Some studies demonstrated changes in metabolic biomarkers such as insulin and insulin-like growth factors. However, further investigation is required to support these findings because these results are not consistent.