Comparison of 2002 TNM nodal status with lymph node density in node-positive patients after radical cystectomy for bladder cancer: Analysis by the number of lymph nodes removed

Objective: Because 2002 TNM pathologic nodal (pN) status was established in patients from whom a relatively small number of lymph nodes had been removed, it is necessary to validate this staging system in current clinical practice, in which the removal of more lymph nodes is recommended during radical cystectomy and pelvic lymphadenectomy. We assessed the ability of lymph node density (LND) and 2002 TNM pathologic nodal (pN) status to predict disease-specific survival (DSS) in node-positive patients after radical cystectomy for bladder cancer, and investigated whether these factors were affected by the number of lymph nodes removed during pelvic lymphadenectomy. Materials and methods: We retrospectively evaluated outcomes in 130 patients with nodal metastases after radical cystectomy performed between 1989 and 2006. Patients were divided into 2 subgroups based on the median number of lymph nodes removed, those with <15 and those with ≥15 lymph nodes removed. The effect of several variables on DSS was assessed. Results: The overall 5-year DSS rate was 38.5%. Multivariate analysis showed that in the entire cohort, LND (HR = 2.28, 1.04-5.03, P = 0.041) and the use of adjuvant chemotherapy (HR = 2.68, 1.42-5.06, P = 0.002) were significant predictors of DSS. In patients with <15 lymph nodes removed, pN status (HR = 5.19, 1.24-21.75, P = 0.024) and use of adjuvant chemotherapy (HR = 6.23, 2.32-16.73, P < 0.001) were independent predictors of DSS. In patients with ≥15 lymph nodes removed, however, only LND (HR = 4.08, 1.10-15.10, P = 0.036) was a predictor of DSS. Conclusions: LND was an independent predictor of DSS in node-positive patients. However, when small numbers of lymph nodes were removed, TNM pN status was a better predictor than LND. These findings suggest that abilities of TNM pN status and LND in node-positive patients to predict DSS could be affected by the total number of lymph nodes removed.