OBJECTIVE: We examined the association between NSAID use and breast cancer recurrence in a prospective cohort of 2,292 early-stage breast cancer survivors diagnosed from 1997 to 2000 participating in the Life After Cancer Epidemiology (LACE) Study. METHODS: From 2000 to 2002, mailed questionnaires were used to obtain information on aspirin, ibuprofen, and other NSAID use and subsequent breast cancer events. A total of 270 recurrences (local, regional, and distant disease and new primary breast cancers) were reported and verified by medical record review. Cox proportional hazard models were used to estimate rate ratios (RR) and 95% confidence intervals (CI), adjusting for age at diagnosis, race, cancer stage, tamoxifen treatment, chemotherapy use, body mass index, and cyclooxygenase-2 (COX2) inhibitor use. RESULTS: Current, regular use (at least three days per week at time of questionnaire administration) of ibuprofen (RR, 0.56; 95% CI, 0.32-0.98), but not aspirin (RR, 1.09; 95% CI, 0.74-1.61), was associated with a statistically significant decreased risk of breast cancer recurrence. The combination of ibuprofen and other non-aspirin NSAIDs such as naproxen and sulindac reflected a similar reduction in risk (RR, 0.56; 95% CI, 0.33-0.95). No association was found for the non-NSAID analgesic acetaminophen. CONCLUSION: Our findings provide support for an inverse association between current, regular ibuprofen use and breast cancer recurrence.