Knowledge gaps and implementation needs for expanding oncologist-led germline genetic testing.

77 Background: Approximately 5-10% of breast cancers, 13-25% of ovarian cancers, 6% of metastatic prostate cancers, and 4-7% of pancreatic cancers are associated with pathogenic variants (PVs) in cancer predisposition genes. Results of germline genetic testing (GGT) are important for informing cancer prevention, screening, and treatment. With the rapid expansion of eligibility criteria for GGT, oncologists increasingly initiate testing themselves, rather than utilizing referrals to genetic counselors, despite limited formalized training in interpretation and counseling on genetic testing results. We sought to identify knowledge gaps and implementation needs in oncologist-led GGT. Methods: Semi-structured interviews were conducted with 13 providers (7 medical oncologists, 2 surgical oncologists, 4 genetic counselors) at New York-Presbyterian Columbia and Hudson Valley. Interviews were transcribed verbatim and coded in Dedoose using a thematic analysis approach. We focused on current practices, perceived patient experiences, strengths and weaknesses of oncologist-led genetic testing, and opportunities for improving current practices. Results: Among patients with cancer, medical and surgical oncologists are comfortable initiating GGT with pre-test counseling focusing on how testing can impact cancer management, such as decisions regarding contralateral prophylactic mastectomy or treatment with PARP inhibitors. Providers agree that all patients with identified PVs should be referred to genetic counselors for further guidance on implications for screening for other cancers and for cascade testing for family relatives, however practices for managing variants of unknown significance (VUSs) are inconsistent. Most oncologists lack a system for following up VUS reclassifications and lack consistent workflows for discussing VUSs with patients. Oncologists and genetic counselors agree the shift towards oncologist-led GGT reduces wait times by reducing appointment burden, enabling GGT to be sent more promptly, and allowing genetic counselors to focus on patients with complex needs. However, genetic counselors find patients are not always adequately counseled by oncologists, and confusion regarding VUSs may result in patients not being appropriately referred to genetic counselors. Conclusions: The shift towards oncologist-led GGT has overall benefits such as reduced wait times, fewer appointments, and timelier GGT results to guide treatment decisions. However, further efforts are needed to improve care quality, such as better pre-testing counseling and increasing oncologists’ knowledge of VUS results. Next, we plan to interview patients who have had oncologist-led GGT to better understand strengths and opportunities for improvement in oncologist-led GGT processes.