The clinical features of extragonadal germ cell tumors: A SEER analysis.

Abstract

e16064 Background: Extragonadal germ cell tumor is an uncommon type of malignancy. We aim to identify the clinical features and the prognosis in various histological subtypes in these patients using the Surveillance, Epidemiology, and End Results Program (SEER) database. Methods: We used the (SEER) database to identify the patients with non-gonadal germ cell tumors between 1998-2015. 1299 patients were identified and included in our analysis. Results: 1299 patients had non-gonadal germ cell tumors between 1998-2015. The mean age was 26 years-old. 568 patients (44%) were females and 731 patients (56%) were males. 276 patients (21%) died after a mean follow up time of 41.16 months (1-60 months). The mean overall survival (OS) was 49.4 months (95%CI 48.21-50.52) with the median being unreached. The Females had better OS compared to the males with a Hazard ratio (HR) = 0.50 (95%CI 0.40-0.63). Age more than 60 years-old at the time of diagnosis was associated with a substantially significant increase in mortality with an HR = 43 (95% CI 19.17-94.41). The mediastinal germ cell tumors were associated with worse OS compared to other sites with a HR = 4.69 (95%CI 3.37-6.52). The median OS for Embryonal cell carcinoma was 22 months, and it was associated with worse OS compared to seminoma and other histological subtypes with a HR = 4.10 (95% CI 1.69-9.72) and 2.77 (95% 1.16-6.58) respectively. On the other hand, Seminoma was associated with better OS compared to other histological subtypes with an HR = 0.66 (95%CI 0.52-0.84). Moreover, tumor size less than 80 mm was associated with better OS with a HR = 0.42 (95%CI 0.30-0.64). In multivariate analysis, patients above the age of 60 had worse OS with an HR = 4.04 (95%CI 1.71-9.58), patients with mediastinal germ cell tumors had poorer OS compared to other sites with an HR = 2.38 (95%CI 1.51-3.79). Furthermore, embryonal carcinoma, mixed germ cell tumors and choriocarcinoma were associated with worse OS compared to seminoma and immature teratoma with an HR = 10.39 (95% CI 4.36-24.72), HR = 2.07 (95% CI 1.23-3.46) and HR = 6.16 (95%CI 2.98-12.74) respectively. Conclusions: Non-gonadal seminoma and immature teratoma carry better prognosis compared to other histological subtypes. Also, among non-gonadal germ cell tumors, non-mediastinal seminoma has the best survival outcome.