Lifestyle and Breast Cancer Risk: How Does It All Add Up?

There is good evidence that breast cancer risk is reduced with healthy lifestyles, such as maintaining normal weight, avoiding alcohol and smoking, and being physically active, with less evidence for specific diets. Ogbenna and colleagues investigated scores on a healthy lifestyle index that combined a healthy eating index, physical activity, body mass index, alcohol, smoking, sedentary behavior, and sleep with the risk of breast cancer in a cohort of postmenopausal women. Five race/ethnic groups were included: African American, Japanese American, Latina, Native Hawaiian, and White. They found a 5% reduction in breast cancer risk with each 1-point increase in index score that was relatively consistent within the specific race/ethnic subgroups. The study did not look at change in lifestyle, nor whether improving one risk factor will counteract adverse effects of others. Given the unknown effects of changing a composite index, it is reasonable to advise women to keep weight in the normal range, engage in regular physical activity, avoid alcohol and smoking, and eat a diet to aid in weight maintenance, i.e., high in vegetables and fruits and low in added sugars and processed foods. Future work on lifestyle indices should focus on the variables most strongly related to breast cancer and the effects of change in individual and combined lifestyle factors on risk. See related article by Ogbenna et al., p. 875.