Rectifying referrals: genetics testing is underutilized in rectal cancer patient care

The National Comprehensive Cancer Network recommends microsatellite instability (MSI)/mismatch repair (MMR) testing to guide genetic counseling referrals for Lynch syndrome (LS) in patients with colorectal cancer. Studies show poor adherence with genetic counseling referral guidelines. Colon and rectal cancers are frequently treated as one entity despite molecular, epidemiologic, and biologic differences.

We investigated facility- and patient-level adherence with genetics testing/referral guidelines for LS and other germline mutations among rectal cancer patients at one institution. This is a retrospective review of patients with rectal cancer at a tertiary hospital from 2018 to 2023, excluding years 2020 to 2022 to minimize confounding factors associated with COVID-19. Indications for genetic testing/referrals were based on the Collaborative Group of the Americas on Inherited Colorectal Cancer guidelines.

We sampled 177 patients, aged 27 to 96 years. A total of 149 (84.2%) underwent MMR/MSI testing; 47 (26.6%) were eligible for genetics referral. Nineteen (40.4%) were referred to genetics, and 14 (73.7%) underwent counseling/testing. One patient was diagnosed with LS, two with MUTYH-associated polyposis, and one with BRCA2.

This study demonstrates poor facility-level adherence with MSI/MMR testing recommendations and poor patient-level compliance with genetic referrals in rectal cancer. When recommendations were met, patients with germline mutations benefited from adjustments to their disease management.