LAUSR

OBJECTIVE Epithelioid Trophoblastic Tumor (ETT) is an extremely rare form of Gestational Trophoblastic Neoplasia (GTN). Knowledge on prognostic factors and optimal management is limited. We identified prognostic factors, optimal treatment, and outcome from the world's largest case series of patients with ETT. METHODS Patients were selected from the international Placental Site Trophoblastic Tumor (PSTT) and ETT database. Fifty-four patients diagnosed with ETT or mixed PSTT/ETT between 2001 and 2016 were included. Cox regression analysis was used to identify prognostic factors for overall survival (OS). RESULTS Forty-five patients with ETT and 9 patients with PSTT/ETT were included. Thirty-six patients had FIGO stage I and 18 had stages II-IV disease. Patients were treated with surgery (n = 23), chemotherapy (n = 6), or a combination of surgery and chemotherapy (n = 25). In total, 39 patients survived, including 22 patients with complete sustained hCG remission for at least 1 year. Patients treated with surgery as first line treatment had early-stage disease and all survived. Most patients treated with chemotherapy with or without surgery had FIGO stages II-IV disease (55%). They underwent multiple lines of chemotherapy. Eleven of them did not survive. Interval since antecedent pregnancy and FIGO stage were prognostic factors of OS (p = 0.012; p = 0.023 respectively). CONCLUSIONS Advanced-stage disease and an interval of ≥48 months since the antecedent pregnancy are poor prognostic factors of ETT. Surgery seems adequate for early-stage disease with a shorter interval. Advanced-stage disease requires a combination of treatment modalities. Because of its rarity, ETT should be treated in a centre with experience in GTN.