Analysis of Clinical Stage T2 Prostate Cancer: Do Current Subclassifications Represent an Improvement?

Abstract

PURPOSE: The purpose of this study was to determine whether the extent of palpable cancer within the prostate predicts outcome after radical prostatectomy. PATIENTS AND METHODS: We combined prospectively collected data on 1,755 consecutive clinical stage T2 patients treated with radical prostatectomy alone at four institutions. According to the 1992 American Joint Committee on Cancer tumor-node-metastasis system, 645 (37%) were T2a, 758 (43%) were T2b, and 352 (20%) were T2c. Kaplan-Meier and proportional hazards regression analyses were performed on the 1992 and 1997 T2 subclassifications. After controlling for the effects of prostate-specific antigen (PSA) and biopsy Gleason sum, the two staging systems were compared for their ability to predict recurrence-free survival (RFS). Adjusted RFS curves were constructed using the corrected group prognosis method. RESULTS: Follow-up ranged from 1 to 166 months (median, 26 months). Cancer recurred in 417 (24%) of the T2 patients. The 1992 (P = .005) but not the 1997 (P = .100) T2 subclassification predicted outcome after controlling for PSA and Gleason sum. After covariate adjustment, RFS was 7% higher at 5 years in the 1992 T2a subcategory relative to the T2b subcategory. CONCLUSION: The 1992 American Joint Committee on Cancer system is superior to the 1997 system, and the former adds prognostic information to a model containing pretreatment PSA and Gleason sum. These results suggest that 1992 T2 subclassification derived from palpable findings improves prognostication over the 1997 subclassification.