A study published in *JAMA Oncology* found that 28.8% of invasive breast cancer cases in U.S. women aged 30 and older are attributable to six modifiable risk factors. Led by Dr. Graham Colditz from the Washington University School of Medicine in St. Louis, the research suggests that avoiding these factors could prevent approximately 77,500 new cases annually.
The six modifiable factors identified include a body mass index (BMI) greater than 25 kg/m^2, alcohol intake, physical inactivity, postmenopausal hormone use, a history of benign breast disease, and breast density. Individually, a BMI over 25 accounted for 18% of cases, alcohol intake for 6%, and physical inactivity for 10%. Postmenopausal hormone use was linked to 6.9% of cases, benign breast disease to 4.5%, and breast density to 4%. Researchers used population attributable fraction (PAF) to estimate these proportions, combining data from previous studies, including the Nurses' Health Study.
The findings highlight the potential for breast cancer prevention through lifestyle modifications, although the study is observational and relies on self-reported data, thus not definitively proving direct cause-and-effect. While acknowledging that some factors like breast density are only partially modifiable, experts like Dr. Marisa Weiss from Breastcancer.org emphasized that women have some control over their risk.
