Purpose: Predictors of response or disease control with oral medroxyprogesterone acetate (MPA) therapy in patients with metastatic or recurrence endometrial cancer remain to be elucidated. The purpose of this study was to clarify the effect of MPA in patients with endometrial cancer and identify markers that predict MPA efficacy.
Methods: We retrospectively analyzed clinical and pathological factors in patients who received MPA. Expression of estrogen receptor, progesterone receptor (PgR), androgen receptor, and Ki67 index was assessed with residual tissue samples of endometrial cancer. Expression levels were evaluated semi-quantitatively using the Allred score. Correlations between expression levels and patients' characteristics, response to MPA, and survival were assessed.
Results: We analyzed clinical factors in 40 patients and molecular pathological factors in 27 patients for MPA efficacy. The overall response rate was 35% in all 40 patients and there were 10 patients (25%) with continued complete or partial response for over 5 years. However, higher Allred score for PgR (p = 0.050) tended to be and lower Ki67 labeling index (p = 0.001) were significantly predictive factors for long-term complete or partial response over 5 years. Median progression-free survival was 6.4 (2-217) months and the 5-year progression-free survival rate was 32%. Multivariate analysis showed that Allred score ≥3 for PgR (p = 0.039) was the only significant predictive marker for long-term disease control. There were no severe adverse events that resulted in discontinuation of MPA.
Conclusions: This study suggests the utility of MPA when the Allred score for PgR is ≥3. Future prospective studies are needed to confirm these findings.
Keywords: Allred score; Endometrial cancer; Ki67; Oral medroxyprogesterone acetate; Progesterone receptor.