Proton Therapy for Intracranial Non-Germinomatous Germ Cell Tumors

Abstract

Proton radiation therapy (RT) is the most conformal available RT modality. The survival and progression outcomes among patients with intracranial non-germinomatous germ cell tumors treated with proton RT have not been reported. Retrospective review of 38 patients with NGGCT treated between May 2005 and September 2016 at the Massachusetts General Hospital and Francis H. Burr Proton Center. A subset of 12 patients were enrolled in a prospective protocol. Patients with prior recurrences were excluded. Thirty-eight patients with a median age of 12 years (range 5-22) were identified. Twenty-eight (74%) were male, 10 (26%) were female. 31 (82%) were white. Twenty-one (55%) had hydrocephalus at diagnosis, and 12 (32%) required a shunt. 9 (24%) had evidence of metastatic disease at diagnosis (positive CSF cytology OR disseminated disease). Location of the primary tumor was suprasellar in 12 (32%), pineal in 15 (39%), and bifocal in 10 (26%) patients; one patient had a primary cerebellar tumor. Almost one-third underwent GTR (32% vs. 24% STR, 26% biopsy alone, 18% no surgery). All patients received induction chemotherapy (100%), the majority with 6 alternating cycles of carboplatin/etoposide & ifosfamide/etoposide. Ten patients (26%) had a second look surgery after chemotherapy. RT field was CSI in 26 (68%), WVRT in 11 (29%), and IF-only in 1 (3%). The median CSI dose was 27 Gy RBE (18-36). At a median follow-up of 4.1 years among 35 patients still alive, 5-year PFS was 80%, and 5-year OS was 88%. Of the 5 patients that recurred, 1 recurrence was local, 3 were distant (1 shunt related), and 1 patient had a failure by markers only. Proton RT is associated with excellent local control and overall survival in this large series of a very rare tumor (Table 1).Abstract 1028; Table 1Factors associated with progression-free survival in NGGCTNGGCT3-year PFSp-valueOverall85%Location*0.322Suprasellar100%Pineal77%Bifocal77%Gender0.144Male81%Female100%Disseminated disease at diagnosis0.295Yes100%No82%Field of RT0.187#WVRT81%CSI92%*Suprasellar vs. Pineal/Bifocal #WVRT vs. CSI; only one patient treated with IF-only who recurred at 21 months. Open table in a new tab