Can diet and lifestyle prevent breast cancer: what is the evidence?

Breast cancer is the most common cancer among women in both developed and less-developed countries. Rates of breast cancer are increasing worldwide, with a particular increase in postmenopausal and estrogen receptor-positive cases. The World Cancer Research Fund (WCRF) and American Cancer Society (ACS) cancer prevention guidelines recommend maintaining a healthy weight, undertaking at least 150 minutes of moderate intensity exercise per week, limiting alcohol consumption, and eating a plant-based diet. Observational data link adherence to physical activity and alcohol guidelines throughout life to a reduced risk of developing pre- and postmenopausal breast cancer. Weight control throughout life appears to prevent cases after menopause. Adherence to a healthy dietary pattern does not have specific effects on breast cancer risk but remains important as it reduces the risk for other common diseases, such as cardiovascular disease (CVD), diabetes, and dementia. Emerging data suggest that smoking during adolescence or early adulthood increases later risk of breast cancer. Lifestyle factors appear to modify risk among high-risk women with a family history and those with typical risk of the general population, although their effects among carriers of BRCA mutations are not well defined. Recent expert reports estimate that successful lifestyle changes could prevent 25% to 30% of cases of breast cancer. These reductions will only be achieved if we can implement targeted prevention programs for high-risk women and women in population-based breast screening programs during childhood, adolescence, and early adulthood when the rapidly developing breast is particularly susceptible to carcinogenesis.