S244 An Appraisal of the Referral, Uptake and Outcomes of Genetic Counseling and Testing in Patients With Young Onset Colorectal Cancer

Abstract

Introduction: The incidence of young-onset colorectal cancer (YOCRC) defined as CRC in individuals < 50 years of age is rapidly rising. Germline genetic testing is currently recommended for all patients with CRC< 50 years. Germline pathogenic variants (PV) are detected in 16-20% of patients with YOCRC and many are diagnosed with an actionable PV not typically associated with CRC, highlighting a need for genetic counseling and multi-panel gene testing (MGPT) in these patients. We aimed to determine the rate of referral to genetic counseling, and uptake and outcomes of germline testing in YOCRC patients seen at a tertiary referral center. Methods: Patients diagnosed with YOCRC from 2010-2019 were included. Patients with appendiceal cancer, known family history of a hereditary cancer syndrome and inflammatory bowel disease were excluded. Demographic data including age, sex, race and family history of CRC were extracted from the electronic medical record (EMR).Genetic counseling referral was confirmed through an order in the EMR, clinical documentation in office visits with colorectal surgery, oncology or gastroenterology, or a completed visit with the genetic counselor. Data was analyzed using STATA, Chi-square and t-test and descriptive analyses were included. Results: 793 YOCRC patients (457 male and 336 female) were included. 56% (445) were referred for genetic counseling and 88% of referred patients completed genetic testing. 20.5% had a PV detected; 83% were in CRC associated genes and 18% were in other actionable genes (Table). Referral to genetic counseling was higher in younger patients (mean age= 40 years in those referred vs. mean age= 43 years in those not referred, p < 0.05) and those with a family history of CRC (70% of patients with family history of CRC vs. 53% of patients without family history were referred, p< 0.05) There was no significant association between referral rate and sex or race. Conclusion: Even in a large academic center, the rates of referrals for genetic counseling in patients with YOCRC were documented in only about half the patients. 1 in 5 YOCRC patients had a PV detected. If the 348 patients not referred to genetic counseling underwent testing, an additional 71 patients may be detected with a germline PV. Our findings highlight the need to raise awareness of the importance of genetic counseling and testing in YOCRC patients, and suggest that health systems should consider implementing care pathways to mitigate the potential impact of under-referral. Table 1. - Demographics, Referral to and Uptake of Genetic Counseling and Testing and Outcome of Genetic Testing Number of patients with YOCRC 793 Demographics N (%) Mean (SD) Age 41.9 (6.8) Sex Male 457 (57.6) Female 336 (42.4) Race White 684 (86.3) Black 72 (9.1) Other 37 (4.7) Family History of CRC Yes 280 (40.2) No 417 (59.8) Referral for Genetic Counseling 445 (56.1) Attended Genetic Counseling 390 (87.6) Underwent Genetic Testing 376 (96.4) • Pathogenic Variant Detected 77 (20.5) • Variant of Uncertain Significance Detected 88 (23.4) • No Variant Detected 211 (56.1) Genetic Testing Outcomes Genetic Syndrome Pathogenic Variant Number of Patients Total (%) CRC and polyposis genes N=64 (83%) Lynch syndrome N=37 (48%) MLH1 11 37 (48) MSH2 13 MSH6 8 PMS2 5 FAP N= 15 (19.4%) APC 15 15 (19.4) MYH- Associated polyposis N =10 (12.9%) MUTYH (Biallelic) 6 10 (12.9) MUTYH (Monoallelic) 4 Juvenile polyposis syndrome N = 1 (1.2%) SMAD4 1 1 (1.2) MSH3 (monoallelic) 1 1 (1.2) Other genes N=13 (17%) ATM 4 13 (17) BRCA1/2 4 BLM (monoallelic) 1 CHEK2 2 FLCN 1 CDKN2A 1