Treatment of Primary Central Nervous System Germinomas With Short-course Induction Chemotherapy Followed by Low-dose Radiotherapy Without a Tumor Bed Boost: Prognostic Impact of Human Chorionic Gonadotropin

OBJECTIVE To investigate the clinical utility of short-course induction chemotherapy followed by low-dose radiotherapy without a tumor bed boost in patients with primary central nervous system (CNS) germinomas. METHODS We retrospectively reviewed the clinical records of patients with primary CNS germinomas who received short-course induction chemotherapy (2 cycles of cisplatin 20 mg/m2 plus etoposide 40 or 100 mg/m2 for 5 days) followed by low-dose radiotherapy (dose: 2340 cGy) without a tumor bed boost. Disease-free survival and overall survival served as the main outcome measures. RESULTS Between February 2002 and June 2018, 24 patients (20 males and 4 females; median age: 14.1 y; age range: 7.9 to 21.2 y) with pathology-proven CNS germinomas were included. The median follow-up time was 106 months (range: 17 to 169 mo). Isolated and multifocal lesions were identified in 13 and 11 patients, respectively. Tumor location was as follows: pineal gland (n=17), suprasellar region (n=13), periventricular region (n=7), and basal ganglia (n=2). Five patients had increased levels (>5 mIU/mL) of beta-human chorionic gonadotropin (β-hCG), whereas alpha-fetoprotein concentrations were within the reference range in all participants. A total of 16 patients achieved remission after induction chemotherapy. The complete response rates of patients with increased and normal β-hCG levels were 40.0% and 72.2%, respectively (P=0.208). Low-dose radiotherapy without a tumor bed boost was subsequently delivered to either the whole ventricle (n=16) or the whole brain (n=8), resulting in complete remission in all participants. Compared with patients without increased β-hCG levels, those with β-hCG-secreting germinomas had less favorable 5-year disease-free survival rates (100% vs. 60%, respectively, P=0.000115). CONCLUSIONS Some children with primary CNS germinoma may benefit from short-course induction chemotherapy followed by low-dose radiotherapy to the whole ventricle without a tumor bed boost. The validity of our findings needs to be confirmed in a randomized phase II study for children with β-hCG levels