MRI Far Safer Than CT for Guiding Radiotherapy in Prostate Cancer!
There was a remarkable reduction in bowel and urinary side effects when MRI was used instead of CT to guide stereotactic body radiotherapy (SBRT) for localized prostate cancer, shows a study from the University of California, Los Angeles. Among the first 100 men in the phase 3 MIRAGE trial (Magnetic Resonance Imaging–Guided Versus Computed Tomography–Guided Stereotactic Body Radiotherapy for Prostate Cancer), MRI guidance more than halved the incidence of grade 2 or higher physician-reported genitourinary toxicity within 90 days of the procedure, which fell from 47.1% with CT to 22.4% with MRI. While 13.7% of men had gastrointestinal complications with CT guidance, there wasn't a single case in the MRI arm. The findings were presented Feb. 17 at the American Society of Clinical Oncology Genitourinary Cancers Symposium.
@micky The better outcomes are caused by the enhanced imaging capabilities of MRI, including real time tracking and automatic beam shutoff when the prostate moves too far outside of the treatment boundary. Across the first 100 subjects, 49 men were randomized to MRI-guided SBRT and 51 to SBRT with CT guidance. Their prostates and proximal seminal vesicles were dosed with 40 Gy of radiation in five fractions. Rectal spacing and nodal irradiation were at physician discretion. Patients in the MRI arm also reported significantly fewer urinary symptoms, including urgency, incontinence, burning sensations, and bowel dysfunction, such as pain, diarrhea, and obstruction, among others, at 1 month with MRI guidance. The differences diminished at 3 months with adverse event management in the CT arm.