Clinical outcome of extragonadal germ cell tumors: Retrospective analysis at a single institution in Japan.

Abstract

345 Background: Extragonadal germ cell tumors (EGGCT) are very rare and account for only 2% to 5% of all malignant germ cell neoplasms. Although multimodality treatment, including cisplatin-based chemotherapy and postchemotherapy surgery, has improved the prognosis of patients with EGGCT, few findings are available for these tumors. We therefore performed a retrospective analysis of Japanese patients with EGGCT. Methods: We performed a retrospective review of the medical records of 34 male patients ranging in age from 18 to 62 years (median age, 30 years) treated at our institution between 1982 and 2010. Fifteen patients (44%) had primary mediastinal EGGCT, 16 patients (47%) had primary retroperitoneal EGGCT, and three patients (9%) had primary mediastinal and retroperitoneal EGGCT. Results: Twenty-six patients (76%) had nonseminomatous EGGCT, and eight patients (24%) had seminomatous histology. Surgical procedures were performed in five patients (15%) as induction treatment. Three of them had seminomatous histology and were continuously disease-free after adjuvant chemotherapy. Twenty-nine patients (85%) had received cisplatin-containing regimen as induction therapy. Twenty-three patients underwent post–chemotherapy surgery, and 14 of them (60%) had residual viable malignant cells. On univariate analysis, nonseminomatous EGGCT (P<0.01) and resistance to cisplatin (lack of achievement of CR/PRm- by induction chemotherapy; P<0.01) were identified as negative prognostic factors for survival. Twenty of 34 patients (59%) were alive without disease, and 13 patients with nonseminomatous histology died of disease progression. The overall 10-year survival rate for all patients was 53%. Conclusions: Patients with seminomatous EGGCT have a very good prognosis, while nonseminomatous histology and resistance to cisplatin were found to be negative prognostic factors.