Abstract P5-09-10: Uptake of genetic testing and prevalence of mutations among minority populations: A retrospective cohort study

Abstract

Abstract Background: Hereditary cancer syndromes account for 5-10% of cancers. Limited data exists on the uptake of genetic testing and the prevalence of mutations in minority populations. Objective: To estimate genetic testing uptake and prevalence of mutations in a minority population seeking care in a safety net healthcare system. Methods: We conducted a retrospective cohort study of patients who were assessed at John H Stroger Jr., Hospital of Cook County cancer genetics risk clinic between October 2015 and March 2018 to determine the uptake of genetic testing and the prevalence of genetic mutations. Patients who met National Comprehensive Cancer Network (NCCN) guidelines for genetic testing for hereditary breast and ovarian cancer syndrome (HBOC), Lynch syndrome and familial adenomatous polyposis were included. Data was abstracted through chart review to obtain age, socio-demographics, personal cancer history, primary language, personal and family history of cancer including type of cancer and age at diagnosis, insurance status, genetic testing status and test results. Uptake of testing was calculated as the percentage of patients who underwent testing among those patients who met NCCN criteria for testing. Prevalence of mutations among those patients who underwent testing was determined and compared between different ethnicities using Chi-square test. Results: Of 510 patients offered genetic counseling & testing, 478 (94%) underwent genetic testing. Among those who tested, 34% (n=165) were African American and 45% (n=212) were of Hispanic origin. Prevalence of any mutation was 48%(n=232), Pathogenic mutations were identified in 11% (n=54) of testers and variants of uncertain significance (VUS) were identified in 37% (n=178). Deleterious mutations and VUS rates in patients affected with hereditary cancer syndromes were 13% (n=42) and 39 % (n=132) respectively. Deleterious mutations and VUS rates in women unaffected with cancer were 9% (n=12) and 33 % (n=46) respectively. Overall mutation prevalence did not differ between affected and unaffected patients (p=0.12) or between Black and Hispanic patients (p=0.96). Deleterious mutation rate in Hispanic patients was 15.6% (CI 20.5%-10.7%) and in Black patients was 3.6% (CI 3%-4%). There was a significant difference in the percentage of deleterious mutations between Hispanic and Black patients (p=0.0009) . Conclusion: Genetic testing uptake was high in minority populations. In the Population who were tested prevalence of pathogenic mutations was higher among Hispanics than African Americans. Citation Format: Nagireddy P, Ganschow P. Uptake of genetic testing and prevalence of mutations among minority populations: A retrospective cohort study [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-09-10.