Physical Activity and Breast Cancer Survival-Epidemiologic Evidence and Potential Biologic Mechanisms

To review the biologic mechanisms that may be operative between physical activity and survival after breast cancer.

Physical activity decreases risk of mortality from breast cancer by up to 40%. Several biologic mechanisms have been hypothesized to explain this association. Previous cohort studies and randomized trials have examined the primary mechanisms that appear to be operative, which involve a decrease in sex hormone levels, insulin resistance, and inflammation. The evidence is still inconsistent and several limitations in the existing literature exist. Understanding the biologic mechanisms involved in the association of physical activity and breast cancer survival will provide more precision to physical activity guidelines for cancer survival. To achieve this objective, future research should include direct measurements of physical activity, sedentary behaviour, and health-related fitness to provide a more comprehensive assessment of these factors and their association with biomarkers and survival after breast cancer.