Abstract B20: Genetic testing for inherited colorectal cancer among African Americans and Caucasians in the era of multigene panels

Abstract

Abstract Background: There is little data about ethnic differences in genetic testing for inherited colorectal cancer (CRC) syndromes. We previously found that African Americans were less likely to be tested for inherited CRC syndromes. With the advent of multigene panel testing, we sought to determine whether there are differences in genetic testing among African Americans and Caucasians over the last 4 years. Aim: Compare patterns of genetic testing for inherited colorectal cancer between African Americans and Caucasians with personal history of CRC or colonic polyps seen in a cancer risk clinic at a single academic institution. Methods: We identified patients with personal history of colon polyps or CRC who were seen in our academic cancer risk clinic between 2011-2015. This time period was selected because multigene panels became commercially available. Patient characteristics were compared between patients tested and those who were not tested for CRC syndromes by race. Multigene panel and single syndrome (i.e., Lynch syndrome or FAP) testing between African Americans and Caucasians was compared. All patients in this study signed informed consent to be part of a clinical registry. Results: A total of 171 patients were identified with a personal history of colon polyps and/or CRC from our registry between 2011-2015. Patients had a mean age of 55.5 years, 62% were female, 66% were Caucasian and 22% African American. Of 171 patients, 101 (59%) underwent germline testing and 70 (41%) did not undergo germline testing. Of those who did not have germline testing, 55/70 (79%) were not offered testing, while 13/70 (19%) declined testing. Differences between African Americans (n=40) and Caucasians (n=112) are detailed in Table 1. Fewer African Americans than Caucasians were tested though this was not statistically significant (50% vs. 59.8%, respectively; p=0.19). There was no difference in declined testing between African Americans and Caucasians (20% vs. 17.8%, respectively; p=0.32). Tested African Americans were older than tested Caucasians (57.6 years vs. 51 years, respectively; p=0.04). There were no differences in gender between races among tested patients (p=0.35). There was no difference in multigene panel compared to single syndrome testing by race (p=0.58). Multigene panel testing was performed in 31 (45.6%) Caucasians and 9 (45.0%) African Americans. Conclusion: Overall, about 60% of patients with personal history of colon polyps or cancer seen in an academic cancer risk clinic underwent genetic testing. Regarding differences by race, we noted a trend toward fewer African Americans getting germline testing; however, the difference was not statistically significant. Among tested individuals, African Americans were significantly older. There were no differences in multigene panel versus single syndrome testing between races. Further investigation is required to determine reasons for lower genetic testing in African Americans at older ages, though these differences do not appear to vary by multigene panel versus single syndrome testing approaches. Citation Format: Jessica Stoll, Funmi Olopade, Sonia Kupfer. Genetic testing for inherited colorectal cancer among African Americans and Caucasians in the era of multigene panels. [abstract]. In: Proceedings of the Eighth AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 13-16, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2016;25(3 Suppl):Abstract nr B20.