2359 - Phase II study: Letrozole maintenance therapy after first line chemotherapy in patients with advanced serous and endometrioid ovarian cancer

Background

The role of hormonal therapy in the treatment of advanced ovarian cancer (OC) has not been determined yet. Recently the hormone maintenance therapy (HMT) has been actively discussed.

Methods

70 patients (pts) with serous and endometrioid OC stage Ic-IV after 1^st line chemotherapy (CT) with paclitaxel/platinum agents and complete (CR) or partial response (PR) were enrolled in phase II study. Pts received HMT with letrozole 2,5 mg per day for 5 years or until disease progression. 71 pts with the same criteria who observed after 1^st line CT was taken as retrospective control group. The groups were comparable at baseline including BRCA1/2 status. Paraffin-embedded material (N = 141) after cytoreductive surgery was assessed for presence of estrogen/progesterone receptors (ER/PR) (IGH) and Ki67 in both groups.

Results

Median progression-free survival (PFS) and overall survival (OS) after letrozole maintenance were 18.7 and 51.2 months respectively. In retrospective analysis PFS was significantly longer in letrozole group than in observational group (18.7 and 16.9 months, p = 0.05; HR 0.68, 95%CI 0.44-0.98). There was no any significant difference in overall survival in HMT and observational groups. In the observational group 26 (36,6%) pts received hormone therapy for disease progression later. The expression of ER, PR and Ki67 didn’t have any prognostic and predictive role. Multivariate Cox regression analysis for PFS showed that administration of HMT, stage and response after CT associated with significantly longer PFS. Based on subgroup analysis only pts with stage III-IV with CR after 1^st line had significantly longer PFS than pts who underwent observation: 20.9 vs 17.7 months (p = 0.05; HR 0.56, 95%CI 0.32-0.99).

Conclusions

HMT with letrozole could be effective in pts with advanced serous and endometriod OC stage III-IV with CR after 1^st line CT regardless of tumour grade. Further randomized studies of HMT are needed.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.