Prevalence of Variants of Uncertain Significance in Patients Undergoing Genetic Testing for Hereditary Breast and Ovarian Cancer and Lynch Syndrome.

Hereditary Breast and Ovarian Cancer (HBOC) and Lynch Syndrome (LS) are the most common inherited cancer syndromes identified with genetic testing. Testing, though, commonly reveals variants of uncertain significance (VUSs). This is a retrospective observational study designed to determine the prevalence of pathogenic mutations and VUSs in patients tested for HBOC and/or LS and to explore the characteristics of the VUS population. Patients 18-80 years old that met NCCN criteria for HBOC and/or LS genetic screening were tested between 2006 and 2020 at Mount Auburn Hospital in Cambridge, Massachusetts. A total of 663 patients were included in the study, with a mean age of 50 years old and 90% being females. Pathogenic mutations were identified in 12.5% and VUSs in 28.3%. VUS prevalence was associated with race (-value = 0.019), being particularly higher in Asian populations. Patients with a personal history of breast cancer or family history of breast or ovarian cancer were more likely to have a VUS (personal breast: OR: 1.55; CI: 1.08-2.25; family breast: OR: 1.68; CI: 1.08-2.60, family ovarian OR: 2.29; CI: 1.04-5.45). In conclusion, VUSs appear to be detected in almost one third patients tested for cancer genetic syndromes, and thus future work is warranted to determine their significance in cancer development.