Treatments
All patients received initial maximum safe surgical tumor resection, and then 36 Gy craniospinal radiotherapy with boost to the posterior fossa at the 55.8 Gy cumulative dose with conventional fractionation at 1.8 Gy/d. Radiotherapy was initiated within 31 days after diagnostic surgery for all patients.
There were 9 patients in MTX group refusing chemotherapy after the completion of radiotherapy according to their parents’ willingness. All of these patients developed relapsed disease 6 to 12 months after radiotherapy. Therefore, a second surgery was performed for the relapsed disease, and all of them received chemotherapy within 4 to 6 weeks after surgery in the same procedure as other patients. The remaining 34 patients initiated 8 cycles of chemotherapy after a 4-6-week rest while completing radiotherapy. The chemotherapy regimen consisted of 1.5 mg/m2 vincristine a day given intravenously over 15 min on days 1 and 8, 750 mg/m2 cyclophosphamide a day given intravenously over 3 h on days 1 and 2, and 75 mg/m2 cisplatin a day given on day 1. A single dose of MTX at 12.5 mg (2.5mg per milliliter of 0.9% sodium chloride solution) was given on day 1 in MTX group, while control group received cerebrospinal fluid (CSF) cytology analysis alone. Brain magnetic resonance imaging (MRI) examination and spine MRT were performed routinely after two, four, six and eight cycles of chemotherapy for all patients.