GCT-08. THE PURSUIT OF OPTIMUM TREATMENT FOR NONGERMINOMATOUS GERM CELL TUMOURS (NGGCT) OF THE CNS – A PROGRESS REPORT FROM THE EUROPEAN GROUP (SIOP CNS GCT II)

Abstract

Abstract BACKGROUND Controversy surrounds the optimum treatment for localised nongerminomatous germ-cell-tumours (NGGCT). The European group has employed more dose-intense chemotherapy followed by 54 Gy focal radiotherapy (fRT), whilst others additionally apply whole-ventricular or craniospinal radiotherapy (CSI). Historically, these approaches have led to comparable outcomes. PATIENTS/METHODS SIOP-CNS-GCT-II aimed to improve event free survival (EFS) for NGGCT by standardising the surgical approach for residual disease and by chemotherapy dose escalation in patients identified as high-risk (age <6 years and/or serum/CSF AFP >1000 ng/ml). Standard treatment with four courses of cisplatin, etoposide and ifosfamide (PEI) followed by 54 Gy fRT with 30 Gy CSI for metastatic disease, was retained from the SIOP-CNS-GCT-96 trial for patients not defined as high-risk. Radiotherapy technique (protons or photons) was not dictated in the trial, but the number of cases receiving proton beam therapy has increased over time. Between 02/2012 and 07/2018, 112 patients with NGGCT from eight European countries were treated according to the SIOP-CNS-GCT-II protocol; 89 were standard-risk, and 14 of these were metastatic. This compared with 149 NGGCT patients treated overall in SIOP-CNS-GCT-96, of which 33 were metastatic. RESULTS In SIOP-CNS-GCT-96, 3-year EFS for localised NGGCT receiving PEI chemotherapy and 54 Gy fRT was 0.72, and for metastatic cases, receiving PEI and 30 Gy CSI with boost, 0.68. In SIOP-CNS-GCT-II, 3-year EFS for metastatic cases receiving similar treatment was excellent at 0.94 (p=0.087 compared with SIOP-CNS-GCT-96) but for localised cases, only 0.63 (p=0.032). CONCLUSION To understand the impact of radiotherapy volumes on EFS and guide future trials, a detailed dosimetric study on the patterns of relapses is in progress. In the meantime, based on our current understanding, most participating countries are recommending addition of whole ventricular radiotherapy to fRT for localised NGGCT.