Prognostic significance of teratoma components in germ cell tumor patients undergoing high-dose chemotherapy and autologous stem cell transplantation.

5028 Background: The prognostic significance of a teratoma component in relapsed or refractory germ cell tumors (GCT) treated with high-dose chemotherapy followed by autologous stem cell transplantation (HDCT-ASCT) remains unclear. While teratoma has been extensively studied in earlier treatment lines, data specifically addressing its impact in the transplant setting are limited. Identification of factors influencing outcomes after HDCT is critical for patient selection and treatment optimization. Methods: This single-center retrospective study included 132 GCT patients who underwent autologous stem cell–supported HDCT. Primary tumor specimens were re-evaluated by an experienced pathologist for the presence of a teratoma component. Progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan–Meier method and compared between teratoma-positive and teratoma-negative groups. Univariate Cox regression and predefined subgroup analyses were performed to identify factors associated with survival outcomes. Results: Baseline pathological data were available for 132 patients; 59 (44.7%) had a teratoma component and 73 (55.3%) did not. Baseline clinicopathological characteristics, including age, primary tumor site, stage, IGCCCG risk group, metastatic pattern, biomarker status, and response to first-line therapy, were comparable between groups. After a median follow-up of 55.6 months, median PFS was 6.8 months (95% CI, 4.1–9.6). Median PFS was significantly shorter in teratoma-positive patients compared with teratoma-negative patients (5.6 vs 10.0 months; log-rank p = 0.011). The 2-year PFS rates were 34% and 50%, respectively. Teratoma presence was associated with inferior PFS in univariate analysis (HR 1.77, 95% CI 1.13–2.77; p = 0.013). Median OS was not reached overall; median OS was 68.9 months in teratoma-positive patients and not reached in teratoma-negative patients, with no significant difference between groups (p = 0.986). The 2-year OS rates were similar (64% vs 67%). Subgroup analyses showed numerically poorer OS with teratoma across most strata, without statistical significance. Conclusions: In relapsed or refractory GCT patients undergoing HDCT, the presence of a teratoma component was associated with inferior disease control but not with a statistically significant OS disadvantage, possibly due to limited follow-up. Teratoma status may help identify patients requiring more intensive transplant strategies and early post-transplant treatment optimization. Prospective studies with longer follow-up are warranted.