The prognostic value of LDH in patients with good risk metastatic seminoma treated with single agent carboplatin AUC10.

644 Background: Raised lactate dehydrogenase (LDH) is a surrogate marker for disease burden and an independent adverse prognostic factor for IGCCCG good risk metastatic seminoma patients treated with cisplatin and etoposide-based chemotherapy (Beyer et al, 2021). Patients with a pre-treatment LDH greater than 2.5x the upper limit of normal (ULN), despite still categorized as good risk disease, have a poorer 3-year progression free survival (PFS) of 80% with this combination treatment. Carboplatin Area Under the Curve (AUC) 10 monotherapy is an alternative to cisplatin and etoposide-based chemotherapy, with comparable effectiveness and a better side effect profile. However, the prognostic value of LDH and specific outcomes of patients with raised LDH in patients treated with carboplatin AUC10 has not been evaluated. Methods: A retrospective analysis of outcomes of good risk metastatic seminoma patients treated with carboplatin AUC10 from January 2000 to January 2021 at two supra-regional cancer centres was conducted. Data were extracted using electronic health records. The variables collected included primary tumor location, stage, tumor markers, relapse date, post-relapse treatment and cause of death. Results: 245 patients were identified with a median follow up period of 5.9 years. The primary site of the tumor was most commonly the testes (n=229, 93.5%). 76 (31%) presented with stage 2a, 81 (33%) with stage 2b and 43 (16%) with stage 2c. 14 patients (6%) experienced a relapse, with 11 patients received bleomycin, etoposide and cisplatin as salvage treatment. 24 patients (10%) had LDH levels >2.5 ULN. The 3-year PFS rate for patients with LDH >2.5 ULN was 79.2% versus 95% in LDH <2.5 ULN (p=0.0004). This was comparable to the 80% reported in the high LDH group by Beyer et al. Conclusions: Our results confirm the validity of raised LDH as an adverse prognostic factor in good risk metastatic seminoma patients treated with carboplatin AUC10, with similar PFS outcomes compared to etoposide-cisplatin based chemotherapy described in Beyer et al. Elevated LDH does not appear to be a contraindication to the use of carboplatin AUC10 monotherapy in this patient population and represents a less toxic alternative to etoposide-cisplatin based chemotherapy.