Frequency of Endometrial Cancer Precursors Associated with Lynch Syndrome

Abstract

Abstract Objective: To identify the rate of mismatch repair deficiency in women with endometrial hyperplasia compared with the rate in endometrial cancer. Patients and Methods: A retrospective cohort pilot study was conducted to identify the frequency of mismatch repair deficiency in endometrial hyperplasia specimens, and compare to the known rate in endometrial cancer. A keyword search of the medical record at a single institution was performed to identify 1300 endometrial tissue blocks either from biopsy, curettage, or hysterectomy. After exclusion, cohort of 91 women with endometrial hyperplasia were included for analysis. Patient characteristics for both those with normal and abnormal MMR results were analyzed using the Mann-Whitney U test and Fisher exact test. Immunohistochemical staining was performed to test for mismatch repair deficiency. Results: Among the 91 women with known endometrial hyperplasia specimens who met inclusion criteria, 4 specimens exhibited mismatch repair deficiency. The observed rate of mismatch repair deficiency in hyperplasia (4.4%), was found to be significantly less than that of mismatch repair deficiency seen in endometrial cancer (25%, p< 0.0001). Conclusions: Based on the data, dMMR is not identified at a similar rate in endometrial hyperplasia compared to endometrial cancer. Currently there is no rationale to recommend immunohistochemical staining for mismatch repair deficiency on hyperplasia specimens, and further investigation is recommended to advance screening guidelines for Lynch syndrome.