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Racial Disparities in Comprehensive Cancer Tumor Profiling Testing From Real-World Data Of 100,000 Cancer Patient Records

Authors Francisco M. De La Vega, Brooke Rhead, Yannick Pouliot, and Justin Guinney

Inequities in cancer patient outcomes and healthcare utilization by race and ethnicity are coming to the forefront. Overcoming these inequities requires a better understanding of the extent of such disparities across cancer types and medical interventions. Here, we studied the race and ethnicity of patients receiving tumor profiling for therapy decision support by examining real-world data (RWD) from 100,000 de-identified patient records across major cancer types.

Tumors and normal tissue (when available) were sequenced with the Tempus xT assay, a 648-gene next-generation sequencing panel. Since race and ethnicity metadata are frequently incomplete in RWD, we imputed these categories from continental genetic ancestry inferred from genotypes of 654 ancestry informative markers obtained from sequencing data. Using a heuristic that combines East Asian, African, Amerindian, European, and South Asian ancestry proportions, we imputed Asian (A), Non-Hispanic Black (NHB), Hispanic/Latino/Native American (HIS), and Non-Hispanic White (NHW) categories with <2% error rate (based on available metadata), leaving 3% of unclassified patients due to complex admixture. NHW patients are overrepresented in the cohort at 72% as compared to NHB (11%), HIS (9%) and ASN (5%). We compared the distributions of patients by race/ethnicity categories across specific cancer types against the overall cohort race/ethnicity distributions. These distributions were compared to the expected distribution under the null hypothesis of no relationship by the χ2 test of independence. Significantly (p<0.05) over/under-represented categories in each cancer type were compared to ranks of incidence by race/ethnicities in SEER program data at the national level. Differences are of a smaller magnitude in NHW as compared to the other races/ethnicities.

We observed several differences that are concordant with SEER; for example, overrepresentations of NHB in breast, colorectal, and endometrial cancers, which correspond to high incidences of these cancers for NHB. Notably, we observed several discordances with SEER incidence rate ranks, including underrepresentation of NHB in pancreatic and urinary tract cancers, underrepresentation of NHW in breast and colorectal cancers, overrepresentation of ASN in gallbladder and biliary cancer, and overrepresentation of HIS in colorectal cancer. These differences can be the result of a complex interplay of factors, such as stage of the disease at sequencing, access to early-stage curative therapies, comorbidities/cofactors, access to care, insurance, socioeconomic status, and others.

Nonetheless, our results show that analysis of racial disparities can be performed with RWD, and this information can be useful in studying causes and devising strategies to improve healthcare equity.