Ability of the 1992 and 1997 American Joint Committee on Cancer staging systems for prostate cancer to predict progression-free survival after radical prostatectomy for stage T2 disease

Purpose: In a revised 1997 edition the American Joint Committee on Cancer (AJCC) staging for prostate cancer reduced the subdivision of T2 disease from 3 (T2a, T2b and T2c) to 2 substages by combining single lobe disease (T2a and T2b) into a single stage, now termed T2a. We retrospectively reviewed a large series of men with clinically organ confined prostate cancer who underwent surgery by a single surgeon to determine how this change affected the ability of the staging system to predict outcome. Materials and Methods: Of 2,293 cases treated with radical prostatectomy from 1982 to 1998, 1,314 were clinically staged to have T2 disease. We analyzed the freedom from biochemical prostate specific antigen (PSA) progression after radical prostatectomy according to the 1992 and 1997 AJCC staging criteria. Results: Overall the actuarial 5 and 10-year biochemical progression-free survival rates for the whole group were 82% and 71%, respectively. The actuarial recurrence-free rate was significantly different for patients with 1992 AJCC T2a (T2a92) versus T2b (T2b92) disease (p <0.0001) but similar for those with 1992 T2b versus T2c (T2c92) disease (p = 0.1165). The actuarial recurrence- free rate was significantly different for patients with 1997 AJCC T2a (T2a97) versus T2b (T2b97) disease (p = 0.0001). However, the overall recurrence-free rate was lower in the T2a97 group compared with the T2a92 group. Conclusions: The 1992 AJCC staging of T2 prostate cancer yielded a significant difference in the outcome of patients with single lobe disease (T2a92 and T2b92), which is obscured by the 1997 staging criteria. Therefore, we believe that the next revision of the AJCC staging system should revert back to the 1992 AJCC system of subdividing a single lobe disease category into T2a and T2b. Alternatively the committee may want to merge T2b92 and T2c92 stages into a new staging entity, since there was no statistical difference in the outcome of these 2 groups.