Breast Cancer and Lifestyle Factors: Umbrella Review.

Lifestyle factors play a major role in the risk of breast cancer. This review aimed to examine the size of the effect of select lifestyle factors on risk for breast cancer and assess the quality of existing evidence. The authors performed an umbrella review of systematic reviews. The authors found an increased risk for breast cancer associated with obesity, alcohol intake, and smoking and a decreased risk due to physical activity. The evidence for sleep disruption and duration indicates risk for breast cancer, but it is limited in size, statistical significance, and quality of evidence.