Background: Germline testing for hereditary colorectal cancer (CRC) has traditionally been offered to patients with strong cancer family histories, whose colon tumors revealed mismatch repair deficiency (dMMR), and/or individuals diagnosed with CRC under age 50. Underdiagnosis of hereditary cancer syndromes is often attributed to the complexity or unawareness of family history or phenotypic criteria.1,2 The National Comprehensive Cancer Network (NCCN) guidelines for CRC were recently updated (v. 1.2022) to consider germline multigene panel testing (MGPT) evaluation for all individuals with CRC.3,4 Our goal was to evaluate documentation of MGPT in CRC patients referred for molecular residual disease (MRD) testing. Methods: This retrospective cohort study reviewed clinical data submitted to a commercial laboratory for consecutive CRC patients referred from non-academic medical facilities for MRD testing during a two-month study period. Medical diagnoses, treatment history, family history and germline genetic evaluation status were obtained from the test requisition form and pathology reports. Clinical notes were reviewed in 77/80 cases. Results: Of the 80 patients who met criteria for inclusion, 65/80 (81%) had documented MMR testing of their colorectal tumor. Whereas five had abnormal immunohistochemistry, only two (40%) had documented germline results. 19/80 (24%) met NCCN criteria solely based on a personal CRC diagnosis <50 years, but only 1/19 (5.3%) had documented MGPT. Only 5/80 (6%) of all CRC patients had documented MGPT. Conclusion: Our real-world data from the community oncology precision medicine setting suggests that a majority of CRC patients who received MRD testing and met the prior NCCN criteria for MGPT may not have received evaluation beyond routine MMR status. Process and educational improvements are needed in community health settings to increase access and uptake of germline testing in CRC patients regardless of age at diagnosis or MMR status.

Citation Format: Suzanne Schrock-Kelley, Vivienne Souter, Michael Hall, Jeffrey N. Weitzel. A precision medicine gap: limited recognition of colorectal patients eligible for germline testing in molecular residual disease testing setting. [abstract]. In: Proceedings of the AACR Special Conference: Precision Prevention, Early Detection, and Interception of Cancer; 2022 Nov 17-19; Austin, TX. Philadelphia (PA): AACR; Can Prev Res 2023;16(1 Suppl): Abstract nr P043.