MRI target delineation may reduce long-term toxicity after prostate radiotherapy

AbstractBackground and purpose. Aiming for minimal toxicity after radical prostate cancer (PC) radiotherapy (RT), magnetic resonance imaging (MRI) target delineation could be a possible benefit knowing that clinical target volumes (CTV) are up to 30% smaller, when CTV delineation on MRI is compared to standard computed tomography (CT). This study compares long-term toxicity using CT or MRI delineation before PC RT.Material and methods. Urinary and rectal toxicity assessments 36 months after image-guided RT (78 Gy) using CTC-AE scores in two groups of PC patients. Peak symptom score values were registered. One group of patients (n = 72) had standard CT target delineation and gold markers as fiducials. Another group of patients (n = 73) had MRI target delineation and a nickel-titanium stent as fiducial.Results. At 36 months no difference in overall survival (92% in both groups, p = 0.29) or in PSA-relapse free survival was found between the groups (MRI = 89% and CT = 94%, p = 0.67). A significantly smaller ...