 Despite this growing body of evidence supporting the safety and feasibility of progesterone analogues as medical management for CAH and early-stage endometrial adenocarcinoma, little is known about its potential role as neoadjuvant chemotherapy. A recent multicenter collaborative trial coordinated by the Gynecologic Oncology Group evaluated the effect of 400mg intramuscular medroxyprogesterone acetate administered 21-24 days prior to scheduled hysterectomy for endometrioid adenocarcinoma of the uterus. Upon comparing patients post-hysterectomy slides to pre-treatment slides, this study found a partial histologic response rate of 63 among the 59 study subjects using pre-defined criteria modified from Wheeler 2007. A down-regulation of progesterone receptor, progesterone receptor beta, Bcl-2, and Ki-67 was also noted in post-hysterectomy specimens, with lower pre-treatment levels of Ki-67 being significantly associated with increased likelihood of histologic response. No clinical data such as patient characteristics, final tumor stage, or specific surgical procedure ie lymphadenectomy were collected. 