Breast Cancer Risk and Use of Non-steroidal Anti-inflammatory Agents After a Benign Breast Biopsy

Over one million women in the U.S. receive biopsy diagnoses of benign breast disease (BBD) each year, which confer a 1.5-4.0-fold increase in breast cancer (BC) risk. Studies in the general population suggest that non-steroidal anti-inflammatory agents (NSAIDs) lower BC risk; however, associations among women with BBD are unknown. We assessed whether NSAID use among women diagnosed with BBD is associated with lower BC risk. Participants included 3,080 women (mean age = 50.3 + 13.5 years) in the Mayo BBD surgical biopsy cohort diagnosed between January 1, 1992 and December 31, 2001 who completed BC risk factor questionnaires that assessed NSAID use, and whose biopsies underwent detailed pathology review, masked to outcome. Women were followed from date of BBD biopsy to BC diagnosis (main outcome) or censoring (death, prophylactic mastectomy, reduction mammoplasty, lobular carcinoma in-situ or last contact). Median follow-up time was 16.4 + 6.0 years. Incident BC was diagnosed among 312 women over a median follow-up of 9.9 years. Regular non-aspirin NSAID use was associated with lower BC risk (HR=0.63, 95%CI=0.46-0.85; p=0.002) with trends of lower risk (highest tertiles of use versus non-use) for greater number of years used (HR=0.55, 95%CI=0.31-0.97; ptrend=0.003), days used per month (HR=0.51; 95%CI=0.33-0.80;ptrend=0.001) and lifetime number of doses taken (HR=0.53, 95%CI=0.31-0.89; ptrend=0.003). We conclude that non-aspirin NSAID use is associated with statistically significant lower BC risk after a BBD biopsy, including a dose-response effect, suggesting a potential role for NSAIDs in BC prevention among BBD patients.