Prostate Cancer Risk Stratification by Simple Scoring of the Current pT3 Lesions: A Proposal for a New Pathologic T-Staging System

Abstract

Cancer spread beyond the prostate, including extraprostatic extension (other than seminal vesicle or bladder invasion; EPE)/microscopic bladder neck invasion and seminal vesicle invasion (SVI) currently classified as pT3a and pT3b lesions, respectively, does not uniformly indicate poor oncologic outcomes. Accurate risk stratification of current pT3 disease is therefore required. We herein further determined the prognostic impact of these histopathologic lesions routinely assessed and reported by pathologists, particularly their combinations. We assessed consecutive 2892 patients undergoing radical prostatectomy for current pT2 (n = 1692), pT3a (n = 956), or pT3b (n = 244) disease at our institution between 2009 and 2018. Based on our preliminary findings, point(s) were given (1 point to focal EPE, microscopic bladder neck invasion, or unilateral SVI; 2 points to nonfocal/established EPE or bilateral SVI) and summed up in each case. Our cohort had 0 point (n = 1692, 58.5%; P0), 1 point (n = 243, 8.4%; P1), 2 points (n = 657, 22.7%; P2), 3 points (n = 192, 6.6%; P3), 4 points (n = 76, 2.6%; P4), and 5 points (n = 32, 1.1%; P5). Univariate analysis revealed associations of higher points with significantly worse biochemical progression-free survival, particularly when P4 and P5 were combined. In multivariable analysis (P0 as a reference), P1 (hazard ratio [HR], 1.57; P = .033), P2 (HR, 3.25; P < .001), P3 (HR, 4.01; P < .001), and P4 + P5 (HR, 5.99; P < .001) showed significance for the risk of postoperative progression. Meanwhile, Harrell C-indexes for the current pT staging, newly developed point system, and the Cancer of the Prostate Risk Assessment post-Surgical (CAPRA-S) score were 0.727 (95% CI, 0.706-0.748), 0.751 (95% CI, 0.729-0.773), and 0.774 (95% CI, 0.755-0.794), respectively, for predicting progression. We believe our data provide a logical rationale for a novel pathologic T-staging system based on the summed points, pT1a (0 point), pT1b (1 point), pT2 (2 points), pT3a (3 points), and pT3b (4 or 5 points), which more accurately stratifies the prognosis of prostate cancer.