Meta-Analysis Compares MRI-Guided SBRT and CT-Guided SBRT for Prostate Cancer
A newly published review of 29 prospective studies revealed the use of MRI-guided daily adaptive SBRT in the management of prostate cancer was associated with significantly lower risks of acute grade 2 or higher genitourinary (GU) and gastrointestinal (GI) toxicities in comparison to CT-guided non-adaptive SBRT.
For patients with prostate cancer, magnetic resonance imaging-guided daily adaptive stereotactic body radiotherapy (MRg-A-SBRT) has a 12 percent lower risk of genitourinary (GU) toxicity and a 5 percent lower risk of gastrointestinal (GI) toxicity in comparison to computed tomography-guided non-adaptive SBRT (CT-SBRT), according to pooled estimates from a new meta-analysis of 29 prospective studies.
For the meta-analysis, recently published in Cancer, the researchers compared toxicity rates between MRg-A-SBRT and CT-SBRT by reviewing data from a total of 2,547 patients drawn from 29 prospective studies published between January 1, 2018 and August 21, 2022.
The researchers found that MRg-A-SBRT was associated with a 16 percent risk of acute grade 2 or higher (G2+) genitourinary (GU) toxicity in comparison to a 28 percent risk for CT-SBRT. The use of CT-SBRT was associated with a 9 percent risk for G2+ gastrointestinal (GI) toxicity in comparison to 4 percent for MRg-A-SBRT, according to the study.
In comparison to CT-SBRT, the study authors also noted the use of MRg-A-SBRT facilitated a 44 percent reduction in the risk of short-term urinary side effects and a 60 percent reduction in the risk of short-term bowel side effects. The researchers added that MRg-A-SBRT was the only factor in a meta-regression analysis to be associated in the study with acute toxicity outcomes.
“These findings suggest that the technical advantages of precision of radiotherapy delivery afforded by MRg-A-SBRT translate to measurable clinical benefit,” wrote lead study author Jonathan E. Leeman, M.D., who is affiliated with the Department of Radiation Oncology at the Dana Farber Institute/Brigham and Women’s Hospital and Harvard Medical School in Boston, and colleagues.
The study authors noted that the meta-analysis findings do not clarify whether differences between MRI and CT guidance, or differences between adaptive and non-adaptive treatment contributed to the reduced toxicity observed in the study.
However, Leeman and colleagues pointed out that smaller treatment volume and precision of treatment delivery can be facilitated, respectively, by MRI-based contouring and tracking. They added that daily adaptive planning may “substantially limit” treatment dosing in the bladder, urethra/bladder neck and rectum.
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