Prevalence of pathogenic mutations and variants of uncertain significance in patients undergoing hereditary cancer genetic testing in Cambridge, MA.
Authors: Chinmay Jani, Arashdeep Rupal, Omar Al Omari, Lipisha Agarwal, Katherine A. Stafford, Harpreet Singh, Abdul Qadir Dar, Margaret Lotz, Abby Dangelo, Prudence B. Lam
Journal: Journal of Clinical Oncology (2021)

e22506 Background: Genetic testing allows for enhanced prognostication and early intervention in patients with high risk of developing cancer. Genetic testing often reveals variants of uncertain significance (VUS), for which association with disease risk is unclear. The ambiguity of this finding creates a dilemma for patients and providers and has been associated with significant communication error and distress. In this retrospective observational study, we seek to characterize the indications, outcomes, and trends in patients undergoing genetic testing in a community hospital in Cambridge, MA. As our study spanned the beginning of the COVID-19 pandemic, we also assessed its impact on care accessibility. Methods: We included patients undergoing genetic testing at our hospital between December 2019 and October 2020 (n=371). Medical charts were abstracted to identify patient characteristics, family history, indication for genetic testing, genetic findings, and subsequent management. Results: Our population had a mean age of 48 years (SD=15), was predominantly female (88.1%), and had a high proportion of Ashkenazi Jewish descent (15.3%). The vast majority (351, 94.6%) had a family history of cancer, while 123 (33.2%) had a personal history of cancer, most commonly breast (n=89). The most common indications for genetic testing were Hereditary Breast and Ovarian Cancer (HBOC in 280, 75%), Lynch Syndrome (LS in 22, 5.9%), and Familial Adenomatous Polyposis (FAP in 7, 2%). Of patients who met HBOC, LS, or FAP criteria for genetic testing, pathogenic mutations were identified in 9.5% and VUS in 28.6%. Out of total 35 (9.4%) pathogenic mutations found in our entire study population, the most common were in BRCA (9, 25.7%), MUTYH (5, 14.2%), and Lynch genes (3, 8.6%). Out of 103 patients with VUS (27.8%), the most common sites were APC (14) and MSH3 (9). We found no significant trend in genetic counseling consultations over our 11 months study period despite the COVID-19 pandemic (R 2 = 0.006). Conclusions: Among patients who met criteria for genetic cancer screening at a community hospital, 9.5% were found to have a pathogenic mutation while 28.6% were found to have VUS. These numbers are comparable to previously published estimates. Despite advances in our understanding of genetic colon and gynecological cancers, the majority of patients presenting for genetic cancer counseling continue to do so due to breast cancer concerns. Lastly, we noted high efficacy in our conversion of in-person genetics consultations to telemedicine during the COVID-19 pandemic, suggesting telemedicine is a robust format for genetic counselling. Mutations (N): BRCA1 (3), BRCA2 (6); MUTHY (5); MSH2 (2), MSH6 (1); ATM (2), and one each in PALB2, RAD50, RAD51C, RAD51D, Tp53, CDKN2A, APC, F2, SDHA, SDHB, VHL. FANCL, NTHL1.