Multiparametric magnetic resonance imaging-guided salvage radiotherapy in prostate cancer

Aim To analyse the efficacy and toxicity of postprostatectomy SRT in patients with a BCR evaluated with mpMRI. Background Multiparametric magnetic resonance imaging (mpMRI) has the ability to detect the site of pelvic recurrence in patients with biochemical recurrence (BCR) after radical prostatectomy (RP). However, we do not know the oncological outcomes of mpMRI-guided savage radiotherapy (SRT). Results Local, lymph node, and pelvic bone recurrence was observed in 13, 4 and 2 patients, respectively. PSA levels were significantly lower in patients with negative mpMRI (0.4ng/mL [0.4]) vs. positive mpMRI (2.2ng/mL [4.1], p=0.003). Median planning target volume doses in patients with visible vs. non-visible recurrences were 76Gy vs. 70Gy. Overall, mean follow-up was 41 months (6–81). Biochemical relapse-free survival (bRFS) at 3 years was 82.3% and 82.5%, respectively, for the negative and positive mpMRI groups (p=0.800). Three-year rates of late grade ≥2 urinary and rectal toxicity were 14.8% and 1.9%, respectively; all but one patient recovered without sequelae. Conclusion SRT to the macroscopic recurrence identified by mpMRI is a feasible and well-tolerated option. In this study, there were no differences in bRFS between MRI-positive and MRI-negative patients, indicating effective targeting of MRI-positive lesions.