Biochemical failure after radical prostatectomy in men with pathologic organ-confined disease: pT2a versus pT2b

Background: The 1997 TNM staging system for prostate carcinoma defines a pT2a disease as a tumor histologically involving one lobe of the prostate and pT2b disease as a tumor histologically involving both prostatic lobes. Whether this distinction provides prognostic significance is unclear. The authors evaluated biochemical outcomes between men with pT2aN0 and pT2bN0 disease.

Methods: The authors identified 1606 men with organ-confined disease (pT2N0) who were treated with radical prostatectomy between 1982 and 2003 by one surgeon. Clinical characteristics were compared between men with pT2a and pT2b tumors using rank-sum analysis, and prostate-specific antigen (PSA) recurrence data were compared using log-rank analysis. The significant independent predictors of PSA recurrence were determined using a multivariate Cox proportional hazards model.

Results: There were no significant differences between men with pT2a and pT2b tumors at the time of surgery in terms of clinicopathologic characteristics (biopsy and pathologic Gleason score, serum PSA level, clinical stage, and age). Log-rank analysis revealed no significant differences in time to PSA recurrence between men with pT2a and pT2b tumors (P = 0.755). The 10-year PSA progression-free survival rate was 95% (confidence interval [CI], 92-97%) for men with pT2a tumors and 93% (CI, 90-95%) for men with pT2b tumors. Multivariate analysis showed that the significant predictors of PSA recurrence included serum PSA level, biopsy and pathologic Gleason score, and clinical stage. In the current cohort of men with organ-confined disease, pathologic stage (pT2a vs. pT2b) was not a significant predictor of PSA recurrence on multivariate analysis.

Conclusions: There was no difference in PSA recurrence rates between men with pT2aN0 versus pT2bN0 tumors. In men with organ-confined disease, radical prostatectomy provided excellent 10-year PSA progression-free survival regardless of tumor burden (pT2a vs. pT2b). Consideration should be given to modifying the TNM staging system to eliminate substratification of pT2 tumors.