BACKGROUND: Opportunities to prevent late-stage breast cancer within the course of usual care are needed. We evaluate whether clinical encounters offer such opportunities. METHODS: Within seven health care plans, we identified 1298 women aged more than 50 years with early (3 cm), late-stage ( or = 3 cm), or metastatic invasive breast cancer diagnosed during 1995-1999, whose first screening mammogram 13-36 months prior to the diagnosis (index) was negative. We audited all care occurring in the health plans up to 36 months prior to the cancer diagnoses. Ordinal logistic regression compared the frequency of events by disease category. We hypothesized that during the 13-36 months prior to diagnosis, women with late-stage or metastatic breast cancer would have more symptoms and be more likely to have breast-related clinical visits but have less breast screening (clinical breast examination [CBE] or mammography) than women with early-stage disease, thereby indicating clinical opportunities for earlier detection. RESULTS: We found no differences in demographic characteristics across breast cancer stage among the 1298 women. Both before and after the negative index mammogram but during the 13-36 months prior to diagnosis, few women had breast symptoms (5% before index, 8% after), but many sought breast care (86% before index, 90% after) and screening CBE (62% before index, 43% after). Only the occurrence of screening CBE (odds ratio [OR] = 0.73, 95% confidence interval [CI] = 0.56 to 0.95) or screening mammograms (OR = 0.74, 95% CI = 0.57 to 0.97) after the negative index mammogram reduced odds of more severe disease at diagnosis. CONCLUSION: Although the mortality benefit of CBE, or one compared to two year mammography has not been established, we found that women with late-stage breast cancers undetected by screening mammography did not experience opportunities for earlier detection except through CBE or additional screening mammography.