First Danish single-institution experience with radical prostatectomy: impact of surgical margins on biochemical outcome.

Objective: This study aimed to investigate the impact of positive surgical margins (PSMs), stratified by location and extension, on biochemical outcome after radical retropubic prostatectomy (RRP).

Material and methods: The study included data from 605 consecutive patients treated with RRP for localized prostate cancer. Patients with node-positive disease were excluded. Biochemical recurrence-free survival was calculated using the Kaplan-Meier method. Univariate and multivariate analysis was used to assess risk factors.

Results: The overall PSM rate was 35.4%. Eighty-three per cent (82.7%) of these had a single PSM, whereas 17.3% of patients had two or more PSMs. Apical PSMs were present in 42.5% and non-apical in 57.5%. The presence of any PSM had a significant impact on the risk of biochemical recurrence (BR) [hazard ratio (HR) = 3.3, p < 0.0001]. Compared with margin-negative patients, both apical and non-apical PSMs increased the risk of BR (HR = 2.1 and 4.2, p = 0.02 and p < 0.0001, respectively). The number of PSMs also influenced the risk of BR (one PSM: HR = 2.8, p < 0.0001, vs two or more PSMs: HR = 5.5, p < 0.0001). In multivariate analysis, pT category, PSA and prostatectomy Gleason score independently increased the risk of BR. In an exploratory multivariate analysis of pT2 tumours, the impact of apical PSMs on biochemical recurrence-free survival (BRFS) was not statistically significant, although with an HR of 2.1. Non-apical PSM was associated with a significantly increased risk of BR (HR = 3.4, p = 0.01). Number of PSMs did not influence the risk of BR in multivariate analysis.

Conclusion: The presence of PSMs after RRP is associated with a higher risk of BR. Multiple and non-apical PSMs are associated with a significantly higher risk of BR compared to single and apical PSMs.