Survival outcomes of patients with mNSGCTs with and without teratoma in the primary tumor: An international retrospective study.

5036 Background: Recent studies have reported conflicting findings on the outcomes of patients with metastatic nonseminomatous germ cell tumors (mNSGCT) and the presence of teratoma in the primary tumor. To further investigate this association, we conducted an analysis using data from a distinct multicenter hospital databases. Methods: Clinical-pathological data of mNSGCT patients whose primary tumors were available for histologic review and who underwent cisplatin based chemotherapy between 1992-2014 were retrospectively collected from the IRB approved Dana Farber Cancer Institute (DFCI), Vall D'Hebron University Hospital (VHIO), University Hospital Virgen Del Rocio (HUVR) and Instituto Nacional Cancerologia (INC), GCT databases. We stratified NSGCT patients by the presence or absence of teratoma in the primary tumor(T+ vs T-) Demographic, clinical and pathological characteristics were analyzed using X2 test for categorical variables and T test for continuous variables. Kaplan-Meier methods estimated survival. Results: A total of 662 patients were included with a median follow-up of 8 years. 305 (46.1%) patients had teratoma in the primary tumor. Median ages were 28,7 (+- 8,61) and 31,0 years (+- 9,19) in T+ in T- groups respectively. The T+ group was more likely to have a testicular primary (94,4% vs 86,3%, p=0.003). There were no major differences in IGCCCG risk between the two groups, T+ vs T-, good: 155 (50,8%) versus 190 (53.2%); intermediate: 75 (24,6%) versus 60 (16,8%); poor: 66 (21,6%) versus 87 (24,4%), p=0.041. First line chemotherapy consisted of bleomycin, etoposide and cisplatin (BEP) in 233 (76,4%) and 286 (80,1%) of each group. The T+ group had more post- chemotherapy retroperitoneal lymph node dissections and other local resections n=211, 69,2% (95% CI: 59% - 74%) compared to the T- group n=160, 44,8% (95% CI: 37%-50%). There was no significant diference in 10-year survival between T+ and T- patients 79% (95%CI: 77% - 89%) vs. 82% (95% CI: 80% - 91%), p= 0,976 (log-rank). Conclusions: The presence of teratoma in the primary tumor was not an adverse prognostic factor in a series of 662 patients with mNSGCT with a median follow-up of 8 years treated in the modern era with predominantly BEP. Longer follow-up beyond 10 years is needed to see if there is an increased incidence of teratoma related deaths in patients with T+.