Magnetic Resonance Imaging Versus Computed Tomography Guidance for Stereotactic Body Radiotherapy in Prostate Cancer: 2-year Outcomes from the MIRAGE Randomized Clinical Trial
Amar U. Kishan, James M. Lamb, Holly Wilhalme, Maria Casado, Natalie Chong, Lily Zello, Jesus E. Juarez, Tommy Jiang, Beth K. Neilsen, Daniel A. Low, Yingli Yang, John Neylon, Vincent Basehart, Ting Martin, Luca Valle, Minsong Cao, Michael L. Steinberg
Abstract
It has been shown that magnetic resonance imaging (MRI) guidance versus computed tomography (CT) guidance for aggressive margin-reduction (AMR) for stereotactic body radiotherapy (SBRT) in prostate cancer reduces acute toxicity, but the longer-term benefits are unknown. We performed a secondary analysis of MIRAGE, a phase 3 randomized clinical trial of MRI-guided SBRT for prostate cancer, to determine whether AMR with MRI guidance significantly reduced 2-yr physician-scored or patient-reported toxic effects in comparison to CT guidance. The cumulative incidence of 2-yr physician-scored toxicity, defined as grade ≥2 genitourinary (GU) and gastrointestinal (GI) toxic effects according to Common Terminology Criteria for Adverse Events v4.03, were lower with MRI guidance. Cumulative incidence rates of late grade ≥2 toxicity at 2 yr with MRI-guided versus CT-guided SBRT were 27% (95% confidence interval [CI] 19-39%)] versus 51% (95% CI 41-63%) for GU toxicity (p = 0.004), and 1.4% (95% CI 0.2-9.6) versus 9.5% (95% CI 4.6-19) for GI toxicity (p = 0.025). Cumulative logistic regression revealed that MRI-guided SBRT was associated with significantly lower odds of a clinically relevant deterioration in bowel function according to the Expanded Prostate Cancer Index Composite-26 score (odds ratio 0.444, 95% CI 0.209-0.942; p = 0.035) and in the Sexual Health Inventory in Men score (odds ratio 0.366, 95% CI 0.148-0.906; p = 0.03). There were no significant differences in the odds of a deterioration for other quality-of-life metrics. These findings support the hypothesis that aggressive planning for margin reduction for prostate SBRT using MRI leads to continued reductions in toxic effects over 2-yr follow-up. This trial is registered on ClinicalTrials.gov Identifier as NCT04384770.