Conventional-dose chemotherapy as first salvage in germ cell tumors: Outcomes from an Ibero-American multi-institutional cohort.

597 Background: In relapsed or refractory germ cell tumors, two salvage strategies are commonly used: conventional-dose chemotherapy (CDCT) and high-dose chemotherapy (HDCT) with autologous stem cell transplantation. Current evidence remains insufficient to define the optimal approach, and the predictive value of existing risk models has not been prospectively validated. This study describes oncological outcomes according to the International Prognostic Factors Study Group (IPFSG) classification in patients receiving CDCT as first salvage therapy in a multi-institutional Ibero-American cohort (Argentina and Spain), where access to HDCT is limited. Methods: We conducted a retrospective, multi-institutional cohort study including patients with germ cell tumors treated between 2009 and 2023. All received CDCT as first-line salvage therapy. Progression-free survival (PFS) and overall survival (OS) were evaluated according to IPFSG classification. Time-to-event outcomes were analyzed using Cox regression, adjusting for potential confounders. Results: We included 91 patients with a median follow-up of 21 months (IQR 6.7–51). Among them, 40 (47%) achieved complete or partial response with negative markers. Progression-free survival was significantly poorer in patients with high to very high Beyer classification than in those with very low, low, or intermediate risk (HR 2.17, 95% CI 1.07–4.49, p = 0.036). Similarly, overall survival was worse in the high to very high group (HR 2.46, 95% CI 1.22–4.90, p = 0.008). Median PFS and OS for patients refractory to first-line treatment were 11 and 17 months, respectively, versus 45 and 70 months for non-refractory patients. Conclusions: While CDCT remains a feasible option for salvage therapy in settings with limited HDCT access, prospective studies are needed to refine risk models and optimize strategies. CDCT appears appropriate for non-refractory and low-risk patients; however, alternative or intensified therapies are required for those with higher risk. Baseline characteristics (n = 91). Primary site Testis 79 (87%) Histology Non seminoma 74 (83%) Non pulmonary visceral metastasis Yes 20 (23%) Refractory to first line 1 Yes 44 (48,3%) IPFSG 2 Very Low 10 (11%) Low 9 (9,9%) Intermediate 31 (34,1%) High 30 (33%) Very High 10 (11%) Chemotherapy regimen TIP 3 72 (79%) 1 Patients were considered refractory to first-line therapy if the PFI was <6 months from the start of treatment. 2 International Prognostic Factors Study Group. 3 Paclitaxel, Ifosfamide, Cisplatin.