Percent tumor volume vs American Joint Committee on Cancer staging system subclassification for predicting biochemical recurrence in patients with pathologic T2 prostate cancer

Abstract

Here, we re-checked the American Joint Committee on Cancer 7th edition subclassification and confirmed the possibility of percent tumor volume as a prognostic factor for biochemical recurrence in the 8th edition subclassification. A total of 1073 patients with pathologic T2 stage disease who underwent radical prostatectomy were included. Exclusion criteria were neoadjuvant therapy and pathologic T3 and N1 disease. Biochemical recurrence-free survival was estimated using the Kaplan-Meier method. Cox hazard regression was used to predict biochemical recurrence. According to the 7th edition subclassification, 141 patients (13.1%) had T2a, 43 (4.0%) had T2b, and 889 (82.9%) had T2c disease. The 7th edition subclassification did not differ significantly on Kaplan-Meier analysis (p = 0.502). Mean percent tumor volume was 8.7 ± 8.0% (interquartile range, 5-10%). Percent tumor volume was positively correlated with initial prostate-specific antigen, grade group, surgical margin, and T2 subclassification (all p < 0.001). The 7th edition subclassification was not a significant factor, whereas percent tumor volume was (hazard ratio, 1.023; 95% confidence interval, 1.005-1.041; p = 0.0128) on multivariate analysis. On Kaplan-Meier analysis, percent tumor volume (> 7.5% vs ≤ 7.5%) differed significantly for biochemical recurrence-free survival (p < 0.001). The 7th edition pathologic T2 subclassification had poor prognostic value for biochemical recurrence in our cohort. Elimination of the 8th edition subclassification was suitable. Percent tumor volume classified biochemical recurrence prognosis in pathologic T2 stage. Therefore, percent tumor volume can be a candidate factor for the next T2 subclassification.