Pediatric Cancer

PD 04 - Pediatrics 1 - Poster Discussion

1028 - Proton Therapy for Intracranial Non-Germinomatous Germ Cell Tumors

Sunday, October 21
4:51 PM - 4:57 PM
Location: Room 217 C/D

Proton Therapy for Intracranial Non-Germinomatous Germ Cell Tumors
R. Sethi1, B. Y. Yeap2, T. I. Yock3, N. J. Tarbell3, and S. MacDonald3; 1Massachusetts General Hospital, Boston, MA, 2Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, 3Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA

Purpose/Objective(s): 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 has not been reported.

Materials/Methods: 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.

Results: 38 patients with a median age of 12 years (range 5-22) were identified. 28 (74%) were male, 10 (26%) were female. 31 (82%) were Caucasian. 21 (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. 10 (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.

Conclusion: Proton RT is associated with excellent local control and overall survival in this large series of a very rare tumor. Table 1: Factors associated with progression-free survival in NGGCT
NGGCT

3-year PFS p-value
Overall 85%
Location* 0.322
Suprasellar 100%
Pineal 77%
Bifocal 77%
Gender 0.144
Male 81%
Female 100%
Disseminated disease at diagnosis 0.295
Yes 100%
No 82%

Field of RT

0.187#
WVRT 81%
CSI 92%
*Suprasellar vs. Pineal/Bifocal #WVRT vs. CSI; only one patient treated with IF-only who recurred at 21 months

Author Disclosure: R. Sethi: None. B.Y. Yeap: None. T.I. Yock: Research Grant; NIH, NIH/NCI. Board Member; Board Member for Home Away Boston. N.J. Tarbell: None.

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