Critical analysis of the 2010 TNM classification in patients with lymph node–positive bladder cancer: Influence of lymph node disease burden

ObjectivesIn 2010, a new TNM staging system was published by American Joint Committee on Cancer, changing the nodal classification to include the presence of common iliac lymph node (LN) involvement as N3 category. The objective of this study was to define the capability of the current TNM nodal classification to separate patients with different prognostic stages and to evaluate the effect of LN disease burden.Methods and materialsA total of 93 patients with metastatic LNs after radical cystectomy and extended LN dissection for urothelial carcinoma of the bladder between 1999 and 2012 were included. The median follow-up was 21.5 months. The correlation between N3 and indicators of LN disease burden was analyzed using the Spearman correlation coefficient. Recurrence-free survival (RFS) and overall survival (OS) analysis was performed using the Kaplan-Meier and Cox proportional hazards methods.ResultsThe presence of N3 disease was associated with higher number of metastatic LNs (7 vs. 2, P<0.01); however, this was highly variable and correlation coefficients between common iliac metastatic LNs and other lymphatic disease burden indicators demonstrated weak association (0.39–0.63). Patients with N1 lesions were found to have a distinct RFS and OS (P<0.01 and P = 0.01, respectively). A trend toward worse RFS (P = 0.07) and OS (P = 0.08) was observed in patients with N3 lesions. However, no difference in RFS or OS was found between patients with N2 and N3 lesions (P = 0.83 and 0.50, respectively).ConclusionsThe N3 category in the current TNM classification defines a group of patients with high but heterogeneous disease burden. This may be the explanation for its lack of prognostic stratification when compared with N2 category bladder cancer.