(HealthDay News) — MRI-guided radiotherapy offers significant benefits over CT-guided radiotherapy for prostate cancer, according to a study published in JAMA Oncology.

Researchers assessed whether the aggressive margin reduction allowed by MRI guidance vs CT guidance would result in reduced toxic effects after stereotactic body radiotherapy (SBRT) in patients with prostate cancer. The phase 3 study included 156 patients — 79 who had MRI-guided SBRT and 77 who had CT-guided SBRT.

Patients in the MRI group were significantly less likely than those in the CT group to have acute grade 2 or higher genitourinary toxic effects (24.4% and 43.4%, respectively; P =.01) or gastrointestinal toxic effects (0.0% and 10.5%, respectively; P =.003).

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At 1 month, fewer patients in the MRI group than in the CT group had a 15-point or higher increase in International Prostate Symptom Score (6.8% and 19.4%, respectively; P = .01) or a clinically significant (≥12-point) decrease in Expanded Prostate Cancer Index Composite-26 bowel scores (25% and 50%, respectively; P = .001).

“In this randomized clinical trial, compared with CT-guidance, MRI-guided SBRT significantly reduced both moderate acute physician-scored toxic effects and decrements in patient-reported quality of life,” the study authors wrote. “Longer-term follow-up will confirm whether these notable benefits persist.”

Several authors disclosed financial ties to ViewRay, maker of the MRI-guided radiation therapy system used in the study.

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