Does Preoperative Magnetic Resonance Imaging Reduce the Rate of Positive Surgical Margins at Radical Prostatectomy in a Randomised Clinical Trial?

BACKGROUND: Magnetic resonance imaging (MRI) has the potential to help the surgeon tailor radical prostatectomy (RP) more accurately according to the location and extent of the tumour and thereby reduce the rate of positive surgical margins (PSMs). OBJECTIVE: To evaluate the benefit of performing MRI prior to RP. DESIGN, SETTING, AND PARTICIPANTS: This single-institution randomised trial included 438 patients between December 2009 and June 2012 who were scheduled for robot-assisted laparoscopic prostatectomy. The study was registered (ClinicalTrials.gov identifier NCT01347320). INTERVENTION: Patients were preoperatively randomly assigned to non-MRI or MRI groups. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary end point was the difference in the PSM rates between the two groups. Secondary end points were the rates of PSMs in clinical subgroups. Summary statistics were extracted from descriptive analyses, chi-square, or Fisher exact test, and logistic regression was used to analyse the data according to the intention-to-treat principle. RESULTS AND LIMITATIONS: A total of 216 patients were randomised to non-MRI; 222 were randomised to MRI. There were 49 cases (23%) of PSMs in the non-MRI group and 43 cases (19%) in the MRI group (p=0.4). The relative and absolute risk reduction was 15% and 4%, respectively. Patients with cT1 constituted 55% of the cohort, in which the rate of PSMs was 27% in the non-MRI group and 16% in the MRI group (p=0.035). The relative and absolute risk reduction was 41% and 11%, respectively. A limitation was suboptimal communication between the radiologist and urologist. CONCLUSIONS: MRI prior to RP did not reduce the overall risk for PSMs in this patient cohort. However, at subgroup analysis we observed a possible benefit of MRI in patients with cT1. PATIENT SUMMARY: This study could not demonstrate a definite benefit of performing magnetic resonance imaging before surgery for all patients. However, there was a possible improved result in patients in which physical examination could not detect the cancer.