Influence of Primary Care on Breast Cancer Outcomes Among Medicare Beneficiaries

PURPOSE: We used the Surveillance Epidemiology and End Results (SEER)-Medicare database to explore the association between primary care and breast cancer outcomes. METHODS: Using a retrospective cohort study of 105,105 female Medicare beneficiaries with a diagnosis of breast cancer in SEER registries during the years 1994-2005, we examined the total number of office visits to primary care physicians and non-primary care physicians in a 24-month period before cancer diagnosis. For women with invasive cancers, we examined the odds of diagnosis of late-stage disease, according to the American Joint Commission on Cancer (AJCC) (stages III and IV vs stages I and II), and survival (breast cancer specific and all cause) using logistic regression and proportional hazards models, respectively. We also explored whether including noninvasive cancers, such as ductal carcinoma in situ (DCIS), would alter results and whether prior mammography was a potential mediator of associations. RESULTS: Primary care physician visits were associated with improved breast cancer outcomes, including greater use of mammography, reduced odds of late-stage diagnosis, and lower breast cancer and overall mortality. Prior mammography (and resultant earlier stage diagnosis) mediated these associations in part, but not completely. Similar results were seen for non-primary care physician visits. Results were similar when women with DCIS were included in the analysis. CONCLUSIONS: Medicare beneficiaries with breast cancer had better outcomes if they made greater use of a primary care physician's ambulatory services. These findings suggest adequate primary medical care may be an important factor in achieving optimal breast cancer outcomes.