Senior Epidemiologist OM1, Inc Boston, United States
Background: Disparities in breast cancer screening, diagnosis, treatment, and outcomes by race/ethnicity have been extensively studied. Patients of minority race and ethnicity are under-represented in cancer clinical trials, as eligibility criteria may inadvertently exclude certain groups of patients. Less is known about representation of underrepresented groups in real-world data (RWD) sources and cancer registries.
Objectives: To examine attrition across race/ethnicity categories in large, population-based data registries after applying typical eligibility criteria to a population of patients receiving mammography screening, and to compare race/ethnicity characteristics of screened patients with missing and non-missing data in an aggregated tumor registry.
Methods: This retrospective, observational study used integrated electronic medical record, radiology, and tumor registry data from a large population of women in the United States. Race and ethnicity characteristics of a female mammography screening cohort were described before and after applying criteria based on year of screen, age, availability of prior screening (with negative/benign results), and a negative history of breast cancer. In the total screened population, the characteristics of patients with and without missing data in the tumor registry were also described.
Results: In the mammography screening cohort, similar representation across race and ethnicity groups were observed before (N=1,945,461 screens) and after (N=998,650) applying criteria; the proportion of White and non-Hispanic women increased by small amounts (70% to 73% and 73% to 76%, respectively), with corresponding decreases in the proportions of non-White and Hispanic women.
Data in the tumor registries showed more attrition by race/ethnicity; among patients with any registry data available (N=28,586) those with tumor stage available were more likely to be White (74%) and non-Hispanic (86%) versus those missing stage data (65% White, 78% non-Hispanic). However, there was significant variation in patient race/ethnicity and stage missingness by site. When adjusting for site, patient race (p < 0.0001) but not ethnicity (p=0.23) was significantly related to tumor stage availability, with patients of Asian and other race more likely to have missing stage data than White patients.
Conclusions: Application of typical eligibility criteria to a RWD population of women receiving screening mammograms resulted in only modest attrition of patients in minority race/ethnicity groups. In tumor registries, missing data was more pronounced among non-White women. Greater attention to potential under-representation of minority groups in cancer registries is warranted.