Despite many advances in the treatment of breast cancer during the last decade, many breast cancer patients still do not receive appropriate treatment. The year 2000 cancer control objectives for the nation require a 50% decrease in breast cancer mortality. This goal cannot be achieved unless appropriate care is provided to all women with breast cancer. This study examines the role of patient characteristics, health insurance, physician characteristics, competition and local environment factors on the quality of care provided by physicians to breast cancer patients. Developed from a theoretical model of physician behavior, an empirical model was tested to demonstrate how these factors affect the quality of care provided for two specific breast cancer practice patterns: 1) whether a two-step surgical technique was performed and, 2) whether postmastectomy rehabilitation and/or education was provided. Data from the National Cancer Institute Community Cancer Care Evaluation, from 1985-1986 were used and included information about the inpatient and outpatient care provided to 3,972 women with local or regional stage breast cancer from local communities across the United States. Multivariable regression results indicate older patients were significantly less likely to receive appropriate care for both surgical and rehabilitation practice patterns studied: patients 80 years and older were two to three times less likely to receive appropriate care. However, effects for other variables differed for the two practice patterns studied: competition had a significant positive impact on surgical care (Odds ratio (OR) = 1.37, P < 0.01), but a negative impact on rehabilitation care (OR = 0.76, P < 0.01), and only having Medicaid coverage had a significant positive impact on whether rehabilitation care was provided (OR 1.93, P < 0.03), but no effect for whether a two-step procedure was performed. The results from this study have implications for program design and policy initiatives aimed at assuring equity in access to treatment for older women. Moreover, the differential effects of competition on these breast cancer practice patterns may have implications for health care reform efforts that rely exclusively on competitive models without performance-based incentives to ensure appropriate care.