Ancestry-based differences in hereditary cancer genetic testing.

Abstract

e13107 Background: Ancestry-based disparities in genetic testing for the hereditary breast and ovarian cancer (HBOC) genes BRCA1/2 have been well documented, but it is unclear whether this extends to other cancer-risk genes. Given reduced costs and broader access to multi-gene panels, we evaluated ancestry-based differences in the utilization and outcomes of HBOC and pan-cancer panel testing. Methods: Individuals who had genetic testing for BRCA1/2only (2006-2016) or with a multi-gene pan-cancer panel (2013-2016) were assessed. Clinical information was obtained from provider-completed test request forms. The most commonly reported ancestries [European (EU), Latin American/Caribbean (LA/C), African (AF), Asian (AS)] were evaluated. Individuals of Ashkenazi Jewish ancestry were not included in the EU group. Results: The relative utilization of HBOC testing in 2013-2016 increased in AF and LA/C individuals (vs 2006-2013) and was similar to panel testing in all ancestries (Table). The positive mutation rate for panel testing was 6.7%; AF (6.4%), LA/C (6.6%), AS (7.1%), EU (7.1%). The positive rate for HBOC testing from 2006-2013 was 5.7%. Of significance, the HBOC positive rate from 2013-2016 dropped to 4.1% and ancestry-specific positive rates were much lower relative to panel testing (Table). Gene-specific mutation prevalence differed by ancestry, but mutations were identified in a wide range of genes for all ancestries. Possible founder mutations were identified in BRCA1/2 and other genes. Conclusions: In this cohort, broader access to genetic testing has reduced disparities in recent years and panel testing shows improved clinical utility relative to HBOC testing in all ancestries. [Table: see text]