Abstract
Accurate diagnosis of significant prostate cancer (PCa) is essential for effective treatment. Multiparametric magnetic resonance imaging (mpMRI) is increasingly used for lesion detection and biopsy guidance, but its impact on outcomes following radiotherapy remains uncertain. This study assesses the effect of MRI-guided biopsy on biochemical recurrence (BCR) following definitive external beam radiotherapy (EBRT). This single-center, retrospective review included 102 patients with localized PCa who received primary EBRT between 2018 and 2021. The MRI-guided biopsy group underwent both targeted and systematic biopsies, while the non-MRI-guided biopsy group underwent systematic biopsy alone. All patients underwent pre-treatment MRI (pre-RT MRI). Kaplan-Meier analysis compared BCR-free survival between the MRI-guided and non-MRI-guided biopsy groups. Among the 102 patients, 57 underwent MRI-guided biopsy, with 52.9% classified as intermediate-risk. The median follow-up period was 57.2 months. The proportion of very-high-risk patients was significantly greater in the non-MRI-guided biopsy group (24.4% vs. 3.5%, p = 0.01). Seventeen patients in the non-guided biopsy group were staged as T3 with the assistance of the pre-RT MRI. Despite the use of pre-RT MRI in all non-MRI-guided biopsy cases, four patients experienced BCR, whereas no BCR was observed in the MRI-guided biopsy group. The MRI-guided biopsy group demonstrated superior BCR-free survival (p < 0.01) across both intermediate- and higher-risk groups. MRI-guided biopsy was associated with a reduced risk of BCR following definitive EBRT, particularly in intermediate-risk patients. In contrast, systematic random biopsies, even when combined with pre-RT MRI, were linked to poorer intermediate oncologic outcomes.