Evaluation of modern pathological criteria for positive margins in radical prostatectomy specimens and their use for predicting biochemical recurrence

Abstract

To assess the interpretation of modern criteria for evaluating surgical margins (SMs), by examining the incidence of positive SMs (PSMs) and subsequent biochemical recurrence in a single-surgeon series of radical prostatectomy (RP) at two institutions, as the criteria for determining PSMs after RP are subject to individual interpretation, and this might explain some of the variability in biochemical recurrence rates with different rates of PSMs. We reviewed 301 consecutive perineal RPs by one surgeon (T.K.) at Emory University Hospital (EUH) and the Medical University of South Carolina (MUSC), with each pathology department using modern criteria to evaluate the SMs. The SM status and biochemical recurrence (BCR) were analysed, the latter defined as a prostate-specific antigen level of > or =0.2 ng/mL. There were 158 perineal RPs at EUH followed by 143 at MUSC. PSMs were reported in 39 patients (24.7%) at EUH, whereas six (4.2%) were positive at MUSC. The overall BCR rates were similar between the groups, but BCR within margin-positive cases was 100% at MUSC vs 25.6% at EUH (P < 0.01). The presence of tumour at <1 mm from the margin did not increase the rate of BCR compared to those with obvious negative SMs (P = 0.731). In this single-surgeon series, using the same criteria to evaluate the SMs resulted in significantly different PSM rates and margin-positive BCR rates between the institutions. Although the reason for these differences is difficult to determine, the study shows clearly that tumour within 1 mm of the margin should not be classified as margin-positive.