Presence of positive surgical margin in patients with organ-confined prostate cancer equals to extracapsular extension negative surgical margin. A plea for TNM staging system reclassification

Abstract

BackgroundTo test the hypothesis that patients with pT2 and positive surgical margins (SM) have a similar biochemical-recurrence (BCR) risk to patients with pT3a, and negative SM. Moreover, we examined the effect of incorporating positive SM as a higher stage on the discrimination accuracy of the current TNM staging system. Materials and methodsWe evaluated 1,503 prostate cancer patients treated with radical prostatectomy, between 1998 and 2010. Only individuals with pT2N0 or pT3aN0, without neoadjuvant and/or adjuvant therapy, were included. Cox regression analyses tested the relationship between SM status (negative [R0] vs. positive [R1]) and BCR rate, after stratification according to T stage. Predictive accuracy of the current T stage and of a novel T stage, which consider positive SM as a higher stage, was quantified with Harrell's concordance index. ResultsPositive SM rate was 20.3%. The 5-year BCR rates were 96%, 82%, 78%, and 62% for patients with, respectively, pT2R0, pT2R1, pT3aR0, and pT3a1 (all P ≤ 0.03). In multivariable analyses, the BCR rate was 3.6-, 2.5-, and 6.0-fold higher (all P < 0.001) in patients with, respectively, pT2R1, pT3aR0, and pT3aR1 stage relative to patients with pT2R0 stage. The maximum univariable (14.1%) and multivariable (6.9%) discrimination accuracy gains were observed, when tumor stage was stratified into pT2R0 vs. pT2R1/pT3R0 vs. pT3R1. ConclusionsThe presence of positive SM at radical prostatectomy (RP) specimen substantially increases the BCR risk. Patients with pT2R1 have similar BCR risk to patients with pT3aR0. Considering these patients as 1 category substantially improves the discrimination accuracy of the current TNM staging system.