Methods: The National Breast Cancer Organization The Netherlands Breast Cancer Audit (NBCA) (2011 to 2015) and the U.S. Surveillance, Epidemiology, and End Results (SEER) database (2010 to 2013) were compared on structure and content. Data variables were grouped into general, treatment-specific, cancer-specific, and follow-up variables and were matched. As proof-of-concept, mastectomy and immediate breast reconstruction rates in patients diagnosed with invasive breast cancer or ductal carcinoma in situ were analyzed.
Results: The NBCA included 115 variables and SEER included 112. The NBCA included significantly more treatment-specific variables (n = 46 versus 6), whereas the SEER database included more cancer-specific variables (n = 74 versus 26). In patients diagnosed with breast cancer or ductal carcinoma in situ, immediate breast reconstruction was performed in 19.3 percent and 24.0 percent of the breast cancer cohort and 44.0 percent and 35.3 percent of the ductal carcinoma in situ cohort in the NBCA and SEER, respectively. Immediate breast reconstruction rates increased significantly over time in both data sets.
Conclusions: This study provides a first overview of available registry data on breast cancer care in The Netherlands and the United States, and revealed limited data on treatment in the United States. Comparison of treatment patterns of immediate breast reconstruction showed interesting differences. The authors advocate the urgency for an international database with alignment of (treatment) variables to improve quality of breast cancer care for patients across the globe.