Significance of p27 as a predicting marker for medroxyprogesterone acetate therapy against endometrial endometrioid adenocarcinoma

We reported that p27 induced by medroxyprogesterone acetate (MPA) may be involved in the progestin-induced growth suppression of human endometrial adenocarcinoma cells. This study aimed at investigating whether p27 expression could be a predicting marker to evaluate the effectiveness of MPA therapy. The clinical responses of 15 patients with endometrial carcinoma treated with MPA were examined. p27 expression was evaluated by immunohistochemical staining. Percentage of positive nuclear staining was expressed as a strongly positive (SP) labeling index (LI). Before MPA treatment, SP LIs in the effective and noneffective groups were 22.6 +/- 14.3% and 9.1 +/- 9.2%. At 1-6 weeks in the MPA treatment, SP LIs increased in both groups and were significantly higher than those before the therapy. At 7-12 weeks, SP LIs in both groups decreased to the level of pretherapy. At 13-18 weeks, SP LIs in the effective group were 14.9 +/- 5.7%, whereas in the noneffective group, 1.1 +/- 2.0%. The former was significantly higher than the latter. p27 expression could predict the effectiveness of MPA treatment for endometrial carcinoma at an early stage of the 4-month period in MPA therapy and could be a useful predicting marker for MPA.