Improved Clinical Staging System Combining Biopsy Laterality and TNM Stage for Men With T1c and T2 Prostate Cancer: Results From the SEARCH Database

Abstract

A number of studies have failed to show significant differences in outcome following radical prostatectomy between men with palpable, clinically localized prostate cancer (cT2) and those whose tumors are not palpable (cT1c). We determined whether we could improve the prognostic value of the TNM staging system in men with cT1c and cT2 cancers by including information on whether prostate needle biopsy was unilaterally or bilaterally positive. A retrospective survey of 992 patients from the SEARCH (Shared Equal Access Regional Cancer Hospital) Database treated with radical prostatectomy at 4 equal access medical centers between 1988 and 2002 was done. TNM 1992 clinical stage was T1c in 421 patients, T2a in 287, T2b in 202 and T2c in 82. Multivariate analysis was used to examine whether biopsy laterality and clinical stage were significant predictors of surgical margin status, nonorgan confined disease, seminal vesicle invasion, and time to prostate specific antigen (PSA) recurrence following radical prostatectomy. Patients with clinical stages T2b and T2c cancers had similar rates of PSA recurrence, which were significantly higher than in patients with T1c and T2a disease, who also had similar rates of PSA recurrence. Bilateral positive biopsy further stratified patients with T1c and T2a disease (p = 0.01) but not those with T2b and T2c cancers (p = 0.207). Grouping these 1992 clinical stages with biopsy laterality resulted in a new clinical staging system, which was a significant predictor of PSA recurrence following radical prostatectomy (p <0.001). On multivariate analysis whether TNM clinical stage was evaluated as a categorical or continuous variable only PSA, biopsy Gleason score and the new clinical staging system (1992 TNM stage groupings combined with biopsy laterality) were significant independent predictors of time to biochemical recurrence following radical prostatectomy. Combining low (T1c and T2a) and high (T2b and T2c) risk 1992 clinical stages with biopsy laterality (unilateral versus bilateral positive) resulted in a new clinical staging system that was a stronger predictor of PSA recurrence following radical prostatectomy than the 1992 or 1997 TNM clinical staging system. If confirmed at other centers and in men who undergo with other treatment modalities, consideration should be given to revising the current TNM staging system to reflect these findings.