Uptake of germline genetic testing in patients with advanced breast, ovarian, pancreatic, or prostate cancer.

19 Background: With FDA approval of PARP inhibitors for treatment of BRCA1/2 -associated advanced breast, ovarian, pancreatic, and prostate cancer, National Comprehensive Cancer Network guidelines for germline genetic testing (GGT) have expanded for patients with these tumor types since 2019. We aimed to analyze factors associated with GGT uptake in these patient populations. Methods: We conducted a retrospective cohort study among patients diagnosed with metastatic breast and prostate cancer and all stages of ovarian and pancreatic cancer in 2020-2023 at Columbia University Irving Medical Center in New York City. We extracted data from the electronic medical record on demographics (age at diagnosis, sex, race/ethnicity, Jewish ancestry, marital status) and clinical characteristics (tumor type, year of diagnosis, family history of cancer, receipt of somatic testing, genetic counseling, targeted therapy). The primary outcome was receipt of GGT. Descriptive statistics were generated and multivariable logistic regression analyses were used to estimate the association between demographic/clinical factors and GGT uptake. Results: Among 884 evaluable patients, mean age was 67 years (SD, 14) and the study population included 45% Whites, 15% Blacks, 21% Hispanics, and 9% Asians/Others; 14% had Jewish ancestry. Only 16% were seen by a genetic counselor, 66% had undergone GGT, and 57% had somatic testing. After adjustment for confounders, younger age, Jewish ancestry, later year at diagnosis, and family history of breast or pancreatic cancer were significantly associated with GGT uptake. Patients with pancreatic or prostate cancer were about 60% less likely to undergo GGT compared to patients with ovarian cancer. Patients who had somatic testing were over 4.5-fold more likely to receive GGT. No significant differences were observed based upon sex or race/ethnicity. Among patients who underwent GGT, 20% were found to have a PV and over half of patients who received targeted therapy had PVs detected. Conclusions: We observed increasing use of oncologist-led GGT over time with over 65% of patients with advanced breast, ovarian, pancreatic, or prostate cancer undergoing testing, of which 20% had PVs detected. Given the evolution of targeted therapies and the potential downstream impact of known PVs for family members, under-utilization of GGT in patients with pancreatic and prostate cancer as well as older individuals should be addressed in future studies.