Yolk sac tumor of the ovary: a retrospective multicenter study of 33 Japanese women by Tohoku Gynecologic Cancer Unit (TGCU).

Yolk sac tumor (YST) of the ovary is a rare germ cell tumor comprising about 1% of all ovarian malignancies. YST usually occurs as a rapidly growing unilateral tumor in young women. With the introduction of cisplatin, YST has been changed from a fatal tumor to a curable tumor. The standard treatment of YST consists of fertility-preserving surgery and 3 or 4 courses of adjuvant combination chemotherapy with bleomycin, etoposide, and cisplatin (BEP). However, the long-term prognosis of BEP-treated YST patients has not been well studied. We therefore conducted a retrospective multicenter study to investigate the prognostic factors of 33 YST patients, including 25 patients treated with BEP. The median age at initial treatment was 20 years (range 10-53). There were 15 patients (at stage I), one (stage II), 16 (stage III), and one (stage IV). Nominal and grouped numerical values were analyzed by the Kaplan-Meier method. All patients had unilateral tumor, with right-side predominance (23 patients; P = 0.02). Eighteen patients had pure YST, 13 had mixed germ cell tumor with YST component, and other 2 patients were not specified. Twenty-eight patients received fertility-preserving surgery. Twenty-seven patients had optimal surgery with less than 1 cm residual tumor diameter. Median number of chemotherapy courses was 5. Median follow-up period was 49 months. The cumulative 5-year survival rate was 87%. Univariate analysis revealed the following significant prognostic factors (P < 0.05): stage, tumor diameter, and residual tumor. Extensive debulking surgery to minimize residual tumor would improve the prognosis.