What are the real risks for breast cancer?

There is a steady drumbeat of peer-reviewed medical articles relating risks of breast cancer from a variety of factors. Whether or not the reported factors are under the control of any given individual, they have been trumpeted by the lay media and are responsible for the understandable finding among women that breast cancer generates more anxiety than heart disease, even though the number of US women who died of heart disease in 2010 is over seven and a half times the number who fell victim to breast cancer. This article attempts to reduce the anxiety-inducing barrage of these reports by orienting physicians to better understand the validity of reported breast cancer risk factors. We hope to provide this understanding by: explaining the difference between relative and absolute risk, encouraging application of the 95% confidence interval to better evaluate the statistical validity of any given risk factor; placing the reported risk factors in the context of an accepted risk factor like cigarette smoking and lung cancer; and communicating the limits of statistical validity in the absence of reproducibility. This review will, to a small degree, provide a balance to the reports currently dominating the literature.