Significance of progesterone receptors (PR-A and PR-B) expression as predictors for relapse after successful therapy of endometrial hyperplasia: A retrospective cohort study.

OBJECTIVE: After successful progestin therapy for endometrial hyperplasia (EH), the risk of relapse remains. We aimed to assess if immunohistochemical (IHC) expression of progesterone receptor isoforms, PR-A and PR-B, in endometrial glands and stroma in pre-treatment endometrial biopsies were related to relapse of EH.

DESIGN AND SETTING: Biopsy material originated from women with low- and medium-risk EH recruited to a recent Norwegian multicentre randomized trial. Participants (n=153) had been treated for six months with three different progestin regimes.

POPULATION: 135 of the 153 women achieved therapy response and underwent follow-up for 24 months after therapy withdrawal. 55 women relapsed during follow-up. Pre-treatment endometrial biopsies from 94 of the 135 responding women were available for IHC staining.

METHODS: IHC staining was performed separately for PR-A and PR-B and IHC expression was evaluated in endometrial glands and stroma by a histological score (H-score) using light microscopy.

MAIN OUTCOME MEASURE: IHC expression of PR-A and PR-B in endometrial glands and stroma in women with or without relapse of EH.

RESULTS: Low PR-A in endometrial glands (p=0.013) and stroma (p<0.001), and high PR-B in endometrial glands (p=0.001), in pre-treatment endometrial biopsy have a statistically significant association with relapse of EH. Women with a pre-treatment ratio of PR-A:PR-B≤1 have higher risk of relapse (71%) compared to women with a ratio of PR-A:PR-B>1 (19%) (p<0.001).

CONCLUSION: IHC expression of PR-A and PR-B in pre-treatment endometrial biopsy proves valuable as predictors of relapse in EH. This article is protected by copyright. All rights reserved.