Effect of intensity-modulated radiotherapy versus three-dimensional conformal radiotherapy on clinical outcomes in patients with glioblastoma multiforme

Abstract

Background Few studies were reported on the comparison of clinical outcomes between intensity-modulated radiotherapy (IMRT) and three-dimensional conformal radiotherapy (3D-CRT) in the treatment of glioblastoma multiforme (GBM). This study aimed to determine whether IMRT improves clinical outcomes compared with 3D-CRT in patients with GBM. Methods The records of 54 patients with newly-diagnosed GBM from July 2009 to December 2010 were reviewed. The patients underwent postoperative IMRT or 3D-CRT with concurrent and adjuvant temozolomide. Kaplan-Meier method and log rank test were used to estimate differences of patients' survival. Results The median follow-up was 13 months. Of the 54 patients, fifty (92.6%) completed the combined modality treatment. The 1-year overall survival rate (OS) was 79.6%. The pattern of failure was predominantly local. A comparative analysis revealed that no statistical difference was observed between the IMRT group (n=21) and the 3D-CRT group (n=33) for 1-year OS (89.6% vs. 75.8%, P=0.795), or 1-year progression-free survival (PFS) (61.0% vs. 45.5%, P=0.867). In dosimetric comparison, IMRT seemed to allow better sparing of organs at risk than 3D-CRT did (P=0.050, P=0.055). However, there was no significant difference for toxicities of irradiation between the IMRT group and the 3D-CRT group. Conclusions Our preliminary results suggested that delivering standard radiation doses by IMRT is unlikely to improve local control or overall survival for GBM compared with 3D-CRT. Given this lack of survival benefit and increased costs of IMRT, the utilization of IMRT treatment for GBM needs to be carefully rationalized.