Postoperative Radiotherapy for Low Grade Glioma of the Brain

Chun, Ha Chung; Lee, Myung Za

Abstract

PURPOSE
To evaluate the effectiveness and tolerance of postoperative external beam radiotherapy for patients with low grade glioma of the brain and define the optimal radiotherapeutic regimen.
MATERIALS AND METHODS
Between June, 1985 and May, 1998, 72 patients with low grade gliomas were treated with postoperative radiotherapy immediately following surgery. Median age was 37 years with range of 11 to 76 years. Forty one patients were male and 31 patients were female with male to female ratio of 1.3:1. Of those patients, 15 underwent biopsy alone and remaining 57 did subtotal resection. The distribution of the patients according to histologic type was as follows: astrocytomas-42 patients (58%), mixed oligodendrogliomas-19 patients (27%), oligodendrogliomas-11 patients (15%). Two patients were treated with whole brain irradiation followed by cone down boost and remaining 70 patients were treated with localized field with appropriate margin. All of the patients were treated with conventional once a day fractionation. Most of patients received total tumor dose of 5000~5500 cGy.
RESULTS
The overall 5 and 7 year survival rates for entire group of 72 patients were 61% and 50%. Corresponding disease free survival rates for entire patients were 53% and 45%, respectively. The 5 and 7 year overall survival rates for astrocytomas, mixed oligodendrogliomas, and oligodendrogliomas were 48% and 45%, 76% and 56%, and 80% and 52%, respectively. Patients who underwent subtotal resection showed better survival rates than those who did biopsy alone. The overall 5 year survival rates for subtotal resection patients and biopsy alone patients were 67% and 43%, respectively. Forty six patients who were 40 years or younger survived better than 26 patients who were 41 years or older (overall survival rate at 5 years, 69% vs 45%). Although one patient was not able to complete the treatment because of neurological deterioration, there was no significant treatment related acute toxicities.
CONCLUSION
Postoperative radiotherapy was safe and effective treatment for patients with low grade gliomas. However, we probably need prospective randomized trial to define optimal treatment timing and schedule for low grade gliomas and select patient group for different treatment philosophies.