Simultaneous integrated boost intensity-modulated radiotherapy in patients with high-grade gliomas

Abstract

Purpose: We analyzed outcomes of simultaneous integrated boost (SIB) intensity-modulated radiotherapy (IMRT) in patients with high-grade gliomas, compared with a literature review.

Methods and materials: Forty consecutive patients (WHO grade III, 14 patients; grade IV, 26 patients) treated with SIB-IMRT were analyzed. A dose of 2.0 Gy was delivered to the planning target volume with a SIB of 0.4 Gy to the gross tumor volume with a total dose of 60 Gy to the gross tumor volume and 50 Gy to the planning target volume in 25 fractions during 5 weeks. Twenty patients received temozolomide chemotherapy.

Results: At a median follow-up of 13.4 months (range, 3.7-55.9 months), median survival was 14.8 months. One- and 2-year survival rates were 78% and 65%, respectively, for patients with grade III tumors and 56% and 31%, respectively, for patients with grade IV tumors. Age (≤50 vs. >50), grade (III vs. IV), subtype (astrocytoma vs. oligodendroglioma or mixed), and a Zubrod performance score (0-1 vs. >2) were predictive of survival. Of 25 (63%) patients who had recurrences, 17 patients had local failure, 9 patients had regional failure, and 1 patient had distant metastasis. Toxicities were acceptable.

Conclusions: SIB-IMRT with the dose/fractionation used in this study is feasible and safe, with a survival outcome similar to the historical control. The shortening of treatment time by using SIB-IMRT may be of value, although further investigation is warranted to prove its survival advantage.