GCT-17. WHAT IS THE CLINICAL OUTCOME OF PROTON BEAM THERAPY FOR PATIENTS WITH INTRACRANIAL GERM CELL TUMOR IN KOREA?

PURPOSE: To evaluate the clinical outcome of patients with intracranial germ cell tumor treated with proton beam therapy (PBT). MATERIALS AND METHODS: Fifty-seven patients with intracranial germ cell tumor treated with PBT between 2009 and 2016 were retrospectively analyzed. RESULTS: Median follow-up duration was 63.7 months (range, 5.6–204.5). Thirty-seven patients (64.9%) were pure germinoma and 20 patients (35.1%) were non-germinomatous germ cell tumor (NGGCT). All patients except 2 patients received chemotherapy before PBT. Twenty-one patients (36.8%) of localized germinoma were treated with whole ventricle irradiation (WVI), while 36 (63.2%) patients who were diagnosed as disseminated germinoma or NGGCT received cranio-spinal irradiation (CSI). Two patients with pure germinoma in basal ganglia showed disease relapse at 3.0 and 6.9 years after PBT at the primary site and pituitary gland, respectively. There was one patient with NGGCT who died of chemotherapy-related mortality at 4.7 years after PBT while her disease was complete remission. The 7-year progression-free survival and overall survival were 70.8% and 100% for focal germinoma, 100% and 100% for disseminated germinoma, 100% and 100% for focal NGGCTs, and 100% and 80.0% for disseminated NGGCTs, respectively. CONCLUSIONS: PBT of pure germinoma resulted in comparable clinical outcomes to that with photon radiotherapy. Our result for NGGCT is also excellent compared to other reports. Failure patterns of germ cell tumors originating in basal ganglia needs to be assessed in large pooled data.