The Prognostic Value of DCE-MRI Findings before Salvage Radiotherapy after Radical Prostatectomy

SIMPLE SUMMARY: The role of restaging before salvage radiotherapy (sRT) for prostate cancer is still controversial. The aim of the present retrospective study was to investigate the predictive value of dynamic contrast-enhanced-magnetic resonance imaging (DCE-MRI) findings, including the volume and the subsite of the presumed local failure. We found that DCE-MRI at restaging for biochemical failure after radical prostatectomy seems to provide both predictive and therapeutic information. Patients with small lesions at the vesico-urethral anastomosis have an excellent prognosis after sRT. ABSTRACT: Background: To investigate the predictive role of dynamic contrast-enhanced-magnetic resonance imaging (DCE-MRI) findings before salvage radiotherapy after radical prostatectomy (RP). Methods: This retrospective study selected patients with biochemical failure (BF) after RP restaged with DCE-MRI. Patients underwent sRT in 30 fractions delivering 66–69 Gy and 73.5 Gy to the prostatic fossa and to the local failure as per DCE-MRI, respectively. Pelvic nodes were treated to 54 Gy in selected patients. The endpoint was BF after sRT. Results: In total, 236 patients were analyzed and 146 (61.9%) had presumed local failure at DCE-MRI: 54.8%, 23.8% and 21.4% were found at the vesico-urethral anastomosis (VUA), the bladder neck and the retro-vesical space, respectively. The presence of a local failure at DCE-MRI halved the risk of BF; VUA-only location and lesion volume were independently correlated with survival without evidence of biochemical failure (bNED) at multivariable analysis. For patients with VUA-only disease up to 0.4 cc, the 4-year-bNED was 94.6% (95%CI: 80.2–98.6%) as opposed to 80.9% (95%CI: 71.6–87.4%) and 73.7% (95%CI: 63.1–81.8%) for other lesions and no macrodisease, respectively. Conclusions: DCE-MRI at restaging for BF after RP provides predictive and therapeutic information. Patients with small lesions at the VUA have an excellent prognosis after sRT.