Study definitions
High-education status was defined as more than 9 years of education.
Distance from tertiary cancer center was separated into two groups:
close to INCA (≤ 40 km) and far from INCA (>40km). The
histopathologic diagnoses were divided into groups: classic,
anaplastic/large cell, desmoplastic/extensive nodularity, and not
otherwise specified (NOS). The extent of surgical resection was
categorized into two major groups according to the surgeon’s
report: gross total resection (GTR) and subtotal resection (STR) or
biopsy, when there was remaining tumor. Patients were classified as
high-risk (HR) whether they were metastatic, had residual tumor
>1.5cm2 on post-operative MRI. Patients
with localized disease, with residual tumor <1.5cm2 or GTR and
above 3 years were classified as Standard Risk (SR). Diagnosis date was
defined by the date of primary surgery.
Between april/1997 and march/2000, patients received Pre-irradiation
Chemotherapy regimen which consisted of 3 cycles of ifosfamide/etoposide
and 3 cycles of cisplatin/vincristine, with radiation therapy by week
15, with 36Gy CSI plus boost to posterior fossa). After march/2000,
COGA9961 regimen(20) became the standard treatment for children above 3
years. Children were treated with upfront radiation therapy (23.4 Gy CSI
for SR and 36 Gy CSI for HR with concomitant vincristine plus boost up
to 54Gy to posterior fossa and maintenance chemotherapy with 8 cycles of
cisplatin, vincristine and lomustine).