Determinants and effects of positive surgical margins after prostatectomy on prostate cancer mortality: a population-based study.

BACKGROUND: The objective of this population-based study was to assess patient, physician and tumour determinants associated with positive surgical margins after prostatectomy, and to assess the effects of positive surgical margins on prostate cancer-specific survival. METHODS: We included 1'254 prostate cancer patients recorded at the Geneva Cancer Registry who had radical prostatectomy during 1990-2008. To assess factors associated with positive margins, we used logistic regression. We assessed the effects of positive margins on prostate cancer-specific survival by Cox proportional hazard models accounting for numerous other prognostics factors including prostate and tumour volume, the total percentage of tumour, radiotherapy, surgical approach and surgeon's caseload. RESULTS: Among men undergoing prostatectomy, 479 (38%) had positive margins. In the multivariate logistic regression analysis, period, clinical- and pathological T stage, Prostate Specific Antigen (PSA) level, Gleason score and percentage of tumour in the prostate were significantly associated to positive margins. Ten-year prostate cancer-specific survival was 96.6% for the negative margins group and 92.0% for the positive margins group (log rank p = 0.008). In the Cox survival analysis adjusted for tumour characteristics, surgical margin status per se was not an independent prognostic factor while age, pathological T, PSA level and Gleason score remained associated with prostate cancer-specific survival. CONCLUSIONS: More aggressive tumour characteristics were strong determinants for positive margins. Furthermore, surgical margin status per se was not an independent prognostic factor for prostate cancer-specific survival after adjusting by the gravity of the disease in the multivariate analysis.