Efficacy of Stereotactic Conformal Radiotherapy vs Conventional Radiotherapy on Benign and Low-Grade Brain Tumors: A Randomized Clinical Trial

Abstract

Importance: Evidence for application of stereotactic and other conformal radiotherapy techniques in treating brain tumors is largely based on data derived from dosimetric, retrospective, or small prospective studies. Therefore, we conducted a randomized clinical trial of stereotactic conformal radiotherapy (SCRT) compared with conventional radiotherapy (ConvRT) evaluating clinically meaningful end points.

Objective: To compare neurocognitive and endocrine functional outcomes and survival at 5 years in young patients with residual and/or progressive benign or low-grade brain tumors treated with SCRT and ConvRT techniques.

Design, setting, and participants: This phase 3 randomized clinical trial enrolled 200 young patients (ages 3-25 years) with residual or progressive benign or low-grade brain tumors at a single center between April 2001 to March 2012. Patients were randomly allocated (1:1) to either SCRT (n = 104) or ConvRT (n = 96) arms.

Interventions: Patients were randomly assigned to either high-precision SCRT or ConvRT to a dose of 54 Gy in 30 fractions over 6 weeks.

Main outcomes and measures: Detailed neuropsychological and neuroendocrine assessments were performed at preradiotherapy baseline, at 6 months, and annually thereafter until 5 years on longitudinal follow-up. Change in these functional parameters was compared between the 2 arms as the primary end point and overall survival (OS) as the secondary end point.

Results: In total, 200 young patients (median [interquartile range] age, 13 [9-17] years; 133 males and 67 females) were enrolled. Mean full-scale or global intelligence quotient (IQ) and performance IQ scores over a period of 5 years were significantly superior in patients treated with SCRT compared with those treated with ConvRT (difference in slope = 1.48; P = .04 vs difference in slope = 1.64; P = .046, respectively). Cumulative incidence of developing new neuroendocrine dysfunction at 5 years was significantly lower in patients treated with SCRT compared with ConvRT (31% vs 51%; P = .01) while developing a new neuroendocrine axis dysfunction in patients with preexisting dysfunction in at least 1 axis at baseline was also significantly lower in the SCRT arm compared with the ConvRT arm (29% vs 52%; P = .02). Five-year OS in SCRT and ConvRT arms was 86% and 91%, respectively (P = .54).

Conclusions and relevance: In young patients with residual and/or progressive benign or low-grade brain tumors requiring radiotherapy for long-term tumor control, SCRT compared with ConvRT achieves superior neurocognitive and neuroendocrine functional outcomes over 5 years without compromising survival.

Trial registration: clinicaltrials.gov Identifier: NCT00517959.

Figure 1.. CONSORT Diagram

This flowchart demonstrates trial profile recruitment and inclusion of patients in the study. RT indicates radiotherapy.

Figure 2.. Mean and Standard Error of Mean at Various Time Points for the Different Neurocognitive and Endocrine Functions

Shown are the trends and the difference in slopes of the various neurocognitive subdomains in patients longitudinally followed up for 5 years; the difference in slopes between the stereotactic conformal radiotherapy (SCRT) and conventional radiotherapy (ConvRT) arms were compared by linear mixed model. Also shown are the cumulative percentage differences in endocrine dysfunction between SCRT and ConvRT arms. Slope estimates of the 2 groups were compared using t tests. RT indicates radiotherapy.

Figure 3.. Local Control and Overall Survival Rates

A, The local control rate was 95% (95% CI, 88%-98%) for stereotactic conformal radiotherapy (SCRT) and 93% (95% CI, 85%-97%) for conventional radiotherapy (ConvRT) (P = .49). B, The overall survival rate was 86% (95% CI, 76%-92%) for SCRT and 91% (95% CI, 83%-95%) for ConvRT (P = .54).