Postoperative External Beam Radiotherapy for Medulloblastoma

Chun, Ha Chung; Lee, Myung Za

Abstract

PURPOSE
This study was performed to evaluate the effectiveness and tolerance of craniospinal irradiation for patients with medulloblastoma and to define the optimal radiotherapeutic regimen.
MATERIALS AND METHODS
We retrospectively analyzed the records of 43 patients with medulloblastoma who were treated with external beam craniospinal radiotherapy at our institution between May, 1984 and April, 1998. Median follow up period was 47 months with range of 18 to 86 months. Twenty seven patients were male and sixteen patients were female, a male to female ratio of 1.7 : 1. Surgery consisted of biopsy alone in 5 patients, subtotal excision in 24 patients, and gross total excision in 14 patients. All of the patients were treated with craniospinal irradiation. All of the patients except four received at least 5,000 cGy to the posterior fossa and forty patients received more than 3,000 cGy to the spinal cord.
RESULTS
The overall survival rates at 5 and 7 years for entire group of patients were 67% and 56%, respectively. Corresponding disease free survival rates were 60% and 51%, respectively. The rates of disease control in the posterior fossa were 77% and 67% at 5 and 7 years. Gross total excision and subtotal excision resulted in 5 year overall survival rates of 76% and 66%, respectively. In contrast, those patients who had biopsy alone had a 5 year survival rate of only 40%. Posterior fossa was a component of failure in 11 of the 18 recurrences. Seven recurrences were isolated to the posterior fossa. Four patients had neuraxis recurrences, three had distant metastasis alone and four had multiple sites of failure, all involving the primary site.
CONCLUSION
Craniospinal irradiation for patients with medulloblastoma is an effective adjuvant treatment without significant treatment related toxicities. There is room for improvement in terms of posterior fossa control, especially in biopsy alone patients. The advances in radiotherapy including hyperfractionation, stereotactic radiosurgery and 3D conformal radiotherapy would be evolved to improve the tumor control rate at primary site.