Clinical Outcome Of Patients With Metastatic Seminomatous Germ Cell Tumor: Results Of A Single High-Volume Cancer Center In Japan

e15539 Background: Metastatic seminomatous germ cell tumor (GCT) is a rare clinicopathologic entity. Here, we report the results of a retrospective analysis of patients with metastatic seminomatous GCT. Methods: We performed a retrospective review of the medical records of 44 men aged 21–62 years (median age, 35 years) who were treated at our institution between December 1978 and August 2013. Median follow-up was 6.5 years (range, 0.4–27.7 years). The primary site of disease was gonadal in 38 patients and extragonadal in 6. Extranodal metastases were present in 6 patients at lung, in 2 patients at bone and in 1 patient at brain. At the time of diagnosis, 25 patients had elevated serum levels of human chorionic gonadotropin (hCG), and 20 patients had elevated serum levels of lactate dehydrogenase (LDH). Survival curve was calculated by the Kaplan- Meier method. Results: Among 44 patients, 37 (84%) had received cisplatin-based chemotherapy as initial therapy, 5 (11%) had received radiation therapy for metastatic lymph nodes after high orchiectomy. Two patients underwent surgical procedures as an initial treatment under the diagnosis of a mediastinal tumor and a late relapse at retroperitoneal lymph node. After cisplatin-based chemotherapy, 9 of 37 patients achieved a complete response (CR), 27 achieved a marker-negative partial response (PR), and 1 presented progressive disease (PD). Nineteen retroperitoneal lymphnodes dissections and 5 lung metastasectomies were performed as post-chemotherapy surgery. In only 1 case, residual viable malignant cells were shown at retroperitoneal lymph node. The patient who had residual viable cancer cells had no relapse without adjuvant chemotherapy. Among the patients who achieved PR after chemotherapy, 14 were followed-up without excision of the residual masses and no relapse was observed. In total, 38 patients (86%) showed no evidence of disease, 5 patients (11%) died of disease progression, and 1 patient committed suicide without disease progression. The 5-year disease specific survival rate for all the patients was 92%. Conclusions: Patients with advanced seminomatous GCT undergoing cisplatin-based chemotherapy have an excellent prognosis.