Abstract C115: Racial disparities in tumor profiling testing inferred from continental genetic ancestry determination of 100,000 cancer patients

Abstract

Abstract There are well documented disparities in the incidence of cancer and outcomes of treatment across patients of different races and ethnicities. This is credited to a variety of factors which include social, structural, and access to care inequities, as well as biological differences that may correlate with race/ethnicity. We aimed to measure racial differences in testing for cancer therapy decision support using real-world data (RWD) from 100,000 de-identified patients who underwent tumor genomic profiling with the Tempus xT next-generation sequencing assay (targeting 648 genes). A challenge for this analysis is that in RWD race/ethnicity is frequently missing from patients’ records. Instead, we used ancestry-informative markers overlapping assay capture regions to infer continental ancestry proportions: Africa, Americas, Europe, East Asia, and South Asia. Our data show that despite a majority of patients being of European descent (72%), our cohort includes 8 to 12-fold more patients with substantial (>50%) non-European ancestry when compared to The Cancer Genome Atlas. Recognizing the complexity of ancestry and race relationships, we imputed several race/ethnicity categories using ancestry admixture thresholds based on literature and our own analysis, demonstrating less than 2% error with available race/ethnicity labels. With imputation, 85% more Black patients were identified within our cohort. Furthermore, Hispanics/Latinos were substantially overrepresented among those missing ethnicity metadata; using imputed ethnicity labels increased the numbers of this patient population by 150%. Patient subpopulation disparities were estimated through comparison of imputed race/ethnicity distributions with the expected overall cohort-level distributions. We observed significantly lower than expected percentages of Black patients with pancreatic (-18%) and urinary tract cancers (-42%), and White patients with breast (-7%) and colorectal (-5%) cancers, whereas higher than expected numbers of Hispanic/Latino patients with colorectal (+22%) and thyroid (+48%), and Asian patients with gallbladder cancer (+32%) were present (p<0.05, chi-squared test). These disparities are unexpected as compared to the ranking of incidence rates in the SEER database by race/ethnicity. Our results show that genetic ancestry inference on genomic data from tumor profiling can partially compensate for the lack of race/ethnicity information in RWD and allow research on disparities and biological race differences in cancer etiology and outcomes. Citation Format: Francisco M. De La Vega, Yannick Pouliot, Brooke Rhead, Justin Guinney. Racial disparities in tumor profiling testing inferred from continental genetic ancestry determination of 100,000 cancer patients [abstract]. In: Proceedings of the 15th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2022 Sep 16-19; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr C115.