Comparison of incident breast cancer cases in the largest national US tumor registries

Abstract Background This study compared incident breast cancer cases in the National Cancer Database (NCDB) and Surveillance, Epidemiology, End Results Program (SEER) to a national population cancer registry. Methods Patients with malignant or in situ breast cancer (BC) 2010–2019 in the NCDB and SEER were compared to the US Cancer Statistics (USCS). Case coverage was estimated as the number of patients in the NCDB/SEER as a proportion of USCS cases. Results The USCS reported 3,047,509 patients; 77.5% patients were included in the NCDB and 46.0% in SEER. Case ascertainment varied significantly by patient sex (both registries, p < .001). For males, 84.1% were captured in the NCDB, whereas only 77.5% of females were included. Case coverage in SEER was better for females than males (46.1% vs. 43.5%). Registries varied significantly by race/ethnicity (both p < .001). Case coverage in the NCDB was highest for non‐Hispanic White (78.2%), non‐Hispanic Black (77.7%), and non‐Hispanic Asian or Pacific Islander (72.5%) BC patients, and lowest for Hispanic (56.4%) and non‐Hispanic American Indian/Alaska Native (41.1%) patients. In SEER, case coverage was highest for non‐Hispanic Asian or Pacific Islander (78.1%) and Hispanic (69.6%) patients and it was significantly lower for all other subgroups (non‐Hispanic Black, 44.8%; non‐Hispanic White, 42.4%; and non‐Hispanic American Indian/Alaska Native, 36.6%). Conclusions National US tumor registries provide data for a large sampling of breast cancer patients, yet significant differences in case coverage were observed based on age, sex, and race/ethnicity. These findings suggest that analyses using these data sets and interpretation of findings should account for these meaningful variances.