A multi-institution analysis of molecular biomarkers in patients with metastatic colorectal cancer in ethnically diverse populations.

Abstract

e16074 Background: Differences in clinical outcomes for metastatic CRC (mCRC) have been reported across racial-ethnic groups, particularly between Hispanics (HA), non-Hispanic Blacks (NHB), and non-Hispanic Whites (NHW), with limited information available among Asian Americans (AA). We examined if there were differences in clinical outcomes by molecular drivers between these groups in a pooled analysis of two institutions serving ethnically diverse patient populations. Methods: We retrospectively examined 1927 mCRC patients from Montefiore Medical Center and the University of Texas MD Anderson Cancer Center. Mutations in KRAS, NRAS, and BRAF were determined by polymerase chain reaction or next generation sequencing. Mutations were then correlated with overall survival (OS). Results: Our patient population consisted of 1153 (61%) NHW, 314 (17%) HA, 320 (17%) NHB and 59 (3.1%) AA. Across subgroups, borderline significant difference in prevalence of BRAF mutation was observed (p = 0.04), with higher prevalence observed among NHW as compared to other groups. No differences were observed for KRAS and NRAS mutation prevalence. In univariate analysis, the median survival for BRAF MT tumors was 18.5 months vs 32 months for BRAF WT tumors (p < 0.0001). Similarly, median OS for KRAS WT, KRAS MT, NRAS WT and NRAS MT was 29.3, 27.4, 31 and 31.5 months respectively, with no differences between groups. In subgroup analysis by race/ethnicity, median OS in BRAF MT NHW was 19.98 months vs 33.48 in BRAF WT NHW (p < 0.0001). Similar trends were observed in HA and NHB. No differences in median OS were observed by KRAS or NRAS mutation status across racial-ethnic groups. Conclusions: This multi-institution study found no meaningful difference in the prevalence of molecular drivers across racial-ethnic groups. Additionally, in our subgroup analyses, OS based on the presence of a specific molecular driver mutation did not seem to vary by race. For example, RAS mutated and BRAF mutated patients showed similar OS across racial-ethnic groups. Our study demonstrates that reported differences in clinical outcomes by race and ethnicity in the literature are unlikely to be dependent on the difference in the presence of certain molecular drivers.