The impact of length and location of positive margins in predicting biochemical recurrence after robot-assisted radical prostatectomy with a minimum follow-up of 5 years

Objective: To evaluate the role of positive surgical margin (PSM) size/focality and location in relation to risk of biochemical recurrence (BCR) after robot-assisted radical prostatectomy (RARP).

Patients and methods: Clinicopathological data were collected from 904 patients who underwent RARP at a single European institution from 2002 to 2006. PSM status after RARP was defined as cancer cells at the inked margin, and was stratified by size/focality and location. The outcome variable was BCR, defined as a postoperative PSA level of ≥0.2 ng/mL. We modelled clinicopathological covariates including PSM size/focality and location using Cox proportional hazards regression. In subgroup analyses, we assessed the effect of PSM size and location at different pathological stages and grades of disease.

Results: Compared with negative SM, a PSM of >3 mm/multifocal was associated with an increased risk of BCR in the entire cohort (hazard ratio [HR] 2.84, 95% confidence interval 1.76-4.59), while unifocal PSMs of ≤3 mm were not significantly associated with BCR. In subgroup analyses, the negative impact of >3 mm/multifocal PSM appeared greatest in those with lower postoperative stage and grade of disease. The prognostic role of PSM location was unconfirmed, although data indicated that posterolateral PSMs may be of lower significance in RARP patients. The study is limited by lack of central pathology review, and lack of statistical adjustment for tumour volume, lymph node status, and surgeon volume.

Conclusion: We found that men with >3 mm/multifocal PSMs have a higher risk of BCR than those with unifocal PSMs of ≤3 mm or negative SMs, especially if they have lower risk disease. Posterolateral margins may be of little significance in a RARP population.