Physical activity and breast cancer outcome: a brief review of evidence, current practice and future direction

There have been several publications of large scale studies with long-term follow up addressing the role of physical activity in the management of breast cancer. Of the twelve studies specifically addressing the effect of physical activity on breast cancer survival, eight showed a statistically significant 50% risk reduction in breast cancer mortality in women who engaged in moderate intensity physical activity before and after their diagnosis of breast cancer. Four smaller studies demonstrated no benefit. Almost all of these observational studies predominantly involved white, professional women from North America and Europe. The positive effects of physical activity were seen for all stages of cancer, with the greatest benefit in steroid receptor positive breast tumours. These studies relied on self-reported questionnaires for recording the levels of physical activity. Despite including thousands of patients, published studies offer no data related to the optimum type, duration and timing of physical activity. Only a few studies provided objective data on physical activity, cardio-respiratory and general fitness. Thus, potential role of physical activity in the management of breast cancer remains far from established. If the beneficial effect of physical activity as demonstrated in the observational studies can be replicated in robust, well designed and well-executed prospective randomised controlled trials, this would provide a tremendous opportunity to enhance adjuvant treatment of breast cancer. By adding physical activity to the spectrum of adjuvant therapies offered to women survival from breast cancer may be enhanced.