Impact of volume of irradiation on survival and quality of life in glioblastoma: a prospective, phase 2, randomized comparison of RTOG and MDACC protocols.

Abstract

Though conformal partial-brain irradiation is the standard adjuvant treatment for glioblastoma, there is no consensus regarding the optimal volume that needs to be irradiated. European Organisation for Research and Treatment of Cancer (EORTC) and The University of Texas MD Anderson Cancer Center (MDACC) guidelines differ from the Radiation Therapy Oncology Group (RTOG) in their approach toward peritumoral edema, whereas RTOG and MDACC guidelines differ from EORTC in the concept of boost phase. A scarcity of randomized comparisons has resulted in remarkable variance in practice among institutions. Fifty glioblastoma patients were randomized to receive adjuvant radiotherapy using RTOG or MDACC protocols. Apart from dosimetric and volumetric analysis, acute toxicities, recurrence patterns, progression-free survival (PFS), overall survival (OS), and quality of life (QoL) were compared using appropriate statistical tests. Both groups were comparable with respect to demographic characteristics. Dosimetric analysis revealed significantly lower boost-phase planning treatment volumes and V60 Gy in the MDACC arm (chi-squared, P = .001 and .013, respectively). No significant differences were observed in doses with respect to organs at risk, acute toxicity, or recurrence patterns (chi-squared, P > .05). On the log-rank test, median PFS (8.8 months vs 6.1 months, P = .043) and OS (17 months vs 12 months, P = .015) were statistically superior in the MDACC group.Age, extent of resection, and proportion of whole brain receiving prescription dose were associated with improved PFS and OS on regression analysis. QoL of patients was significantly better in the MDACC group in all domains except cognitive, as assessed with the EORTC Quality of Life Questionnaire (QLQ-C30) and Brain Cancer Module (QLQ-BN20) (general linear model, P < .05). Use of limited-margin MDACC protocol can potentially improve survival outcomes apart from QoL of glioblastoma patients, as compared with the RTOG protocol.