Lynch-like syndrome in endometrial cancer: Features of a growing population.
5585 Background: Current guidelines recommend screening all endometrial cancers (EC) and colorectal cancers (CRC) for defects in DNA mismatch repair (MMR). Tumor screening combined with germline genetic testing can categorize patients into three groups: intact-MMR, Lynch syndrome (LS), and Lynch-like syndrome (LLS). Our objective was to describe features of the growing population of patients with LLS in EC and compare to existing CRC literature. Methods: A systematic search of databases between 1990-2018 identified studies of EC patients with tumor testing (MMR immunohistochemistry or microsatellite instability) and germline assessment for LS. Data on clinicopathologic features was abstracted when available. Associations between LS, LLS, and intact-MMR were analyzed using descriptive statistics. Results: The comprehensive search produced 3,427 publications; 29 met inclusion criteria. Abstracted data and features of each group are presented in the table. Conclusions: In EC, LLS closely resembles LS with younger age at diagnosis, more advanced stage and higher grade as compared to patients with intact-MMR. LLS in EC is similar to intact-MMR in regard to histology, and family history of LS-associated cancer. The CRC literature is limited, but reports LS and LLS have similar stage, grade and histology. In CRC, LS and LLS are diagnosed at a younger age, and are more likely to have family history of LS-associated cancers than intact-MMR. Features of EC with intact-MMR, LLS, and LS. [Table: see text]