Purpose: To assess the outcome and prognostic factors for adult patients with medulloblastoma managed by postoperative radiotherapy between 1958 and 1988 at the Princess Margaret Hospital.
Methods and materials: A retrospective review was undertaken of 48 patients age 16 years or older who received radiotherapy for medulloblastoma. The median age at diagnosis was 25 years, with 36 male and 12 female patients. Sixteen tumors were confined to midline structures, and 32 were localized to a cerebellar hemisphere or involved midline and lateral structures. The desmoplastic variant was reported in 12 cases. Complete macroscopic removal was achieved in 22 patients, subtotal removal in 23, and biopsy only in 3. Forty-six patients received craniospinal radiation and 2 patients received local irradiation only.
Results: Median overall survival was 7.9 years, and 5- and 10-year overall survival was 62% and 41%, respectively. Significant factors for disease-free survival were M stage (M0 vs. M1-4, p = 0.0005), functional state at the time of radiotherapy (1-2 vs. 3-5, p = 0.005), and the absence or presence of hydrocephalus preoperatively (p = 0.02). Twenty-four patients developed recurrent disease, with 14 relapsing first in the posterior fossa. Subtotal removal of tumor (p = 0.04) was the only factor predictive of posterior fossa relapse.
Conclusions: Patients with disease outside the posterior fossa at diagnosis, symptomatic patients (neurologic functional state 3-5) at the time of radiotherapy, and those who present with hydrocephalus have poorer disease-free survival. Gross total resection improved posterior fossa control.