Metformin for the treatment of endometrial hyperplasia.

5592Background: We sought to evaluate the short-term response rate, toxicity and potential molecular changes following treatment with metformin for simple (SEH) and complex endometrial hyperplasia without atypia (CEH). Methods: Women with newly diagnosedsimple or complex endometrial hyperplasia without atypia by endometrial biopsy or dilation & curettage were enrolled onto a prospective multi-institutional single arm clinical trial, and treated with metformin for 3 months (850 mg daily x 4 weeks, then twice daily for 8 weeks), followed by repeat biopsy. Pathologic response and toxicity (CTCAE 4.1) were assessed. Expression of the estrogen (ER) and progesterone (PR) receptor and the metformin transporters (OCT1, OCT3, PMAT, MATE1, MATE2) were evaluated by immunohistochemistry in formalin-fixed, paraffin-embedded endometrial specimens pre- and post-treatment. Slides were scanned using the Aperio ScanScope, and digital images were analyzed using Aperio ImageScope software. We report proportions as %, along w...