Dr. Hensley on dMRR and MSI-H Testing in Endometrial Cancer

Martee L. Hensley, MD, a medical oncologist at Memorial Sloan Kettering Cancer Center, discusses DNA mismatch repair deficiency (dMMR) and microsatellite-instability high (MSI-H) testing for patients with endometrial cancer.

According to Hensley, she receives many questions about whether dMMR testing or MSI-H testing influences endometrial prognosis. There are data showing that dMMR tumors have an increased propensity for having lymphovascular invasion and higher tumor grade—which are adverse prognostic factors. However, the outcomes for patients with dMMR endometrioid cancers were not different, suggesting that the dMMR overcomes those adverse prognostic factors in some way. That may have something to do with immune surveillance, Hensley adds.

The therapeutic implications of dMMR and MSI-H testing comes from recent data with pembrolizumab (Keytruda), which was recently approved by the FDA for use in advanced cancers that have dMMR proteins or are MSI-H, including endometrial cancers. That is another reason to test for these in patients with advanced disease, says Hensley, as it opens up that door to immunotherapy.