Genetic testing and referral patterns of non-BRCA mutation carriers at increased or uncertain risk of ovarian cancer.

Abstract

1585 Background: While the management of BRCA1/2 is clear, management of non-BRCA mutations with increased risk or uncertain risk of ovarian cancer (OC) is not well established. Previously, we reported that referral to a gynecologic oncologist (GO) resulted in a 30-fold increased uptake of risk reducing surgery (RRS). We aimed to identify trends in genetic testing (GT) and referral to a GO of patients (pts) with such mutations. Methods: In this retrospective cohort study at 3 satellite sites within 1 institution from 2014 to 2018, pts were identified by ICD-10 codes Z15.01, Z15.02, Z15.09, Z15.89, C50.919, Q99.8, and C54.1. Pts with mutations with increased risk of OC ( MLH1, MSH2/6, PMS2, EPCAM (LS genes) , RAD51C/D, BRIP1, STK11) and uncertain risk of OC ( PALB2, ATM, BARD1, NBN) were included; BRCA1/2 and variants of uncertain significance were excluded . Outcomes of interest were patterns of GT and referral to a GO. Chi square and logistic regression were used with p < 0.05. Results: Of 20,000 pts with above ICD-10 codes, 240 pts had genes of interest. Mutations in increased risk of OC included: LS genes, 131; BRIP1, 14; RAD51D, 8; RAD51C, 5; STK11, 1. Mutations associated with uncertain risk of OC were: ATM, 43; PALB2, 23; NBN, 10; BARD1, 5. Pts with known mutations prior establishing care at our institution (N = 69) were less likely to be referred to a GO (22% vs 78%, p = 0.015). Pts with LS genes were more likely to be referred to a GO (52% vs. 25%, p < 0.001), to be tested by a GC (52% vs 25%, p < 0.001), and to be tested for family history (FH) of known mutation (69% vs 30%, p < 0.001). Provider performing GT included: genetic counselor (GC), 66 (28%); medical oncologist, 44 (18%); general obstetrician-gynecologist, 44 (18%); breast surgeon, 6 (3%), and primary care provider, 5 (2%). Of 66 pts tested by a GC, 46 (70%) were referred to GO, vs 48/105 (45%) pts who underwent GT by non-GC (p = 0.001). Reasons for GT among pts were: FH of cancer, 113 (47%); personal history of cancer, 56 (23%); known FH of a mutation, 49 (20%); and unknown indication, 22 (9%). When controlling for age, parity, race, insurance, GT provider, and reasons for GT, mutations with increased risk of OC were associated with referral to a GO (OR 3.55, 95% CI 1.88-6.72), along with pts who were tested by a GC (OR 2.65, 95% CI 1.27-5.51). Conclusions: Only ~30% of pts underwent GT by a GC, which was associated with increased referral to a GO. LS genes are better known and were associated with higher uptake of GO referral. Education of OC risks of these newer mutations among providers performing GT may increase referral to a GO and uptake of RRS.