GCT-13. OUTCOMES OF INTRACRANIAL GERMINOMA TREATED AT A SINGLE UK PROTON CENTRE ACCORDING TO UK CHILDREN’S CANCER AND LEUKAEMIA GROUP (CCLG) GUIDELINES

Abstract

Abstract BACKGROUND After SIOP-CNS-GCT II closed in 2018, the CCLG recommended, with caveats, following the standard trial arms: 4 cycles of chemotherapy (Etoposide-Carboplatin alternating with Etoposide-Ifosfamide) followed by whole ventricular radiotherapy (WVRT) (24Gy/15fractions) and boost (16Gy/10fr) to the primary site(s) for localised germinoma and craniospinal irradiation (CSI) (24Gy/15fr) followed by boost (16Gy/10fr) to primary and metastatic sites for metastatic disease. Since 04/2021, the CCLG formally recommended omitting the boost for localised unifocal germinoma in complete radiological response after chemotherapy. From autumn 2022, we also omitted boosts to completely responded primary sites for localised bifocal germinoma. METHODS Retrospective reviewed of all patients referred to our proton centre 12/2018–06/2023. We collected patient, tumour and treatment factors, acute toxicities (CTCAE grade≥3), and event-free survival(EFS) from radiotherapy until 09/2023. RESULTS Forty-two patients (36M:6F) were included, 23 localised and 19 (including 3 incompletely staged) treated as metastatic. Primary sites: 21 pineal, 8 pituitary/suprasellar, 10 bifocal and 3 atypical (optic nerve, periventricular, thalamic). Diagnosis was by histopathology in 40 and bifocal disease with negative CSF and serum markers in 2. Median age was 15 years (IQR 13-16), median follow-up 13 months (IQR 6-15). Patients were treated according to CCLG guidance, apart from three patients with metastatic pure germinoma, of whom one received 2 cycles Cisplatin-Etoposide, and two received 5 and 3 cycles of Vinblastine before CSI, and one patient with metastatic germinoma plus teratoma who received 2 cycles of Cisplatin-Etoposide and non-germinoma radiotherapy doses (30Gy/20fr CSI, 24Gy/15fr cranial boosts). No patient had subsequent surgery. All remained progression free at last follow-up. Eight patients developed acute grade 3 toxicities: 3 vomiting (2 CSI, 1 WVRT), and 5 lymphopenia (all CSI). CONCLUSIONS Disease control was excellent, with no relapses to date. Proton therapy was well tolerated with low rates of acute high grade toxicities.