Six months response rate of combined oral medroxyprogesterone / levonorgestrel-intrauterine system for early-stage endometrial cancer in young women: a Korean Gynecologic-Oncology Group Study

Objective: To evaluate the efficacy of combined oral medroxyprogesterone acetate (MPA)/levonorgestrel-intrauterine system (LNG-IUS) treatment and to compare the diagnostic accuracy of endometrial aspiration biopsy with dilatation & curettage (D&C) in young women with early-stage endometrial cancer (EC) who wished to preserve their fertility. Methods: A prospective phase II multicenter study was conducted from January 2012 to January 2017, Patients with grade 1 endometrioid adenocarcinoma confined to the endometrium were treated with combined oral MPA (500 mg/day)/LNG-IUS. At 3 and 6 months of treatment, the histologic change of the endometrial tissue was assessed. The regression rate at 6 months treatment and the consistency of the histologic results between the aspiration biopsy and the D&C were evaluated. Results: Forty-four patients were enrolled. Nine voluntarily withdrew and 35 patients completed the protocol treatment. The complete regression (CR) rate at 6 months was 37.1% (13/35). Partial response was shown in 25.7% of cases (9/35). There were no cases of progressive disease and no treatment-related complications. A comparison of the pathologic results from aspiration biopsy and D&C was carried out for 33 cases. Fifteen cases were diagnosed as EC by D&C. Among these, only 8 were diagnosed with EC from aspiration biopsy, yielding a diagnostic concordance of 53.3% (kappa=0.55). Conclusion: Combined oral MPA/LNG-IUS treatment for EC showed 37.1% of CR rate at 6 months. Considering the short treatment periods, CR rate may be much higher if the treatment continued to 9 or 12 months. So, this treatment is still a viable treatment option for young women of early-stage EC. Endometrial aspiration biopsy with the LNG-IUS in place is less accurate than D&C for follow-up evaluation of patients undergoing this treatment.