Cancer Program Practice Profile Reports (CP(3)R), established by the Commission on Cancer, are based on 6 guidelines for breast and colorectal cancer care using cancer registry data. The long-term goal is the use of cancer registry data for real-time interventions to optimize the process of individual patient multidisciplinary care.,CP(3)R results using 593 analytic breast cancer cases in 2008 were compared in 3 databases: an institutional breast cancer research database, an institutional cancer registry, and a regional Cancer Surveillance System.,Compliance with the CP(3)R guidelines calculated using the 3 databases was 80% to 98% for radiation therapy following breast-conserving surgery, 78% to 88% for combination chemotherapy of hormone receptor-negative stage T1c, II, or III disease, and 53% to 85% for hormone therapy of hormone receptor-positive stage T1c, II, or III disease. There was a high rate of discrepancy of tumor characteristics, treatment, and CP(3)R resulting from inaccurate and incomplete data.,Using national cancer databases prospectively to monitor and ensure optimal multidisciplinary cancer care will require dramatic changes in cancer registry processes.