Postoperative radiation therapy for medulloblastoma - High recurrence rate in the subfrontal region

Purpose: To investigate the treatment results and analyze the prognostic factors for patients with medulloblastoma (MB) treated by surgery and postoperative radiation therapy (RT). Methods and materials: Thirty-five patients of MB receiving surgery followed by RT from February 1986 to September 1999 were reviewed. Their median age was 12 years with a slight male predominance. Twenty-four (69%) patients had total resection of tumor. Most (86%) cases received craniospinal irradiation (CSI). Adequate dose (craniospinal dose ≥ 30 Gy and posterior fossa dose ≥ 50 Gy) was given in 26 (74%) patients. Results: The median survival duration was 48 months. The 5-year and 10-year overall survival rates were 63% and 40%, respectively. Univariate analysis revealed that stage, shunt surgery, RT dose, and protracted RT course were significant factors in predicting overall survival (OS), disease-free survival (DFS), and/or posterior fossa control (PFC). Multivariate analysis showed that RT dose affected OS and PFC independently, stage influenced OS and DFS, while protracted RT course impacted DFS. A total of 20 cases developed disease relapse. The median time to relapse was 18 months. The posterior fossa (10 cases) was the most common site of first failure, followed by the subfrontal lobe (7 cases), spine (6 cases), and other areas (4 cases). Conclusion: Our results were compatible with others, except that more subfrontal relapse were found. Surgical resection followed by standard dose and adequate margin of CSI are recommended as the mainstays of treatment.