Abstract Code: IUC26681-88

Carboplatin AUC 10 in Good-Prognosis Metastatic Seminoma: A Portuguese Real-World Experience

1. Figueiredo ¹, J. Pedro Barata ¹, S. Magno ¹, F. Vaz ¹

(1) Instituto Português de Oncologia de Lisboa Francisco Gentil – Portugal

High-dose carboplatin has emerged as a potential alternative to cisplatin-based chemotherapy for good-prognosis metastatic seminoma, aiming to reduce acute and long-term toxicity without compromising efficacy. Phase II and retrospective studies report three-year progression-free survival above 93% and overall survival exceeding 96%, with predominantly haematological toxicity. However, this strategy is not yet endorsed by most international guidelines and has seen limited adoption outside the United Kingdom.

This single-centre retrospective study evaluates the acute toxicity and early treatment response of high-dose carboplatin (area under the curve [AUC] 10, every 21 days, 3–4 cycles) in a Portuguese cohort. Efficacy was assessed by post-chemotherapy computed tomography (CT). Adverse events were graded per Common Terminology Criteria for Adverse Events.

Nine male patients were included, with median age 34 years (range 31–41), all Eastern Cooperative Oncology Group performance status 0, with preserved renal function and testicular primary. Most had stage IIB disease (n=5; 55.6%). All metastases were retroperitoneal and most patients (n=5; 55.6%) had recurrent disease.

All patients experienced at least one adverse event (48 events), predominantly haematological: thrombocytopenia (n=8; 88.9%), neutropenia (n=6; 66.7%) and anaemia (n=5; 55.6%). Grade 3–4 events occurred in three patients (33.3%). Non-haematological toxicity was mild (grade 1–2). Four patients (44.4%) required cycle delay and one (11.1%) needed transfusion, but no treatment was suspended. No febrile neutropenia, hospitalisation or treatment-related deaths were recorded.

Seven patients completed treatment, all in an outpatient-setting, and two remain on treatment with a planned 4th cycle. Post-treatment CT (median 50 days, range 39-110) showed complete radiological response in two patients (28.6%), residual disease <3 cm in five (71.4%) and >3 cm in one (14.3%), the latter with only burned-out tumour at resection. With a median follow-up of 23 months (range 15-25), no disease progression was observed.

Despite its small sample size and short follow-up, this study provides real-world evidence supporting the safety and favourable early response of high-dose carboplatin AUC 10 in good-prognosis metastatic seminoma. These findings are consistent with published data and contribute to the growing body of evidence suggesting that a less toxic alternative to cisplatin-based regimens may be within reach.