Standardization of pelvic lymphadenectomy performed at radical cystectomy - Can we establish a minimum number of lymph nodes that should be removed?

BACKGROUND. The number of lymph nodes (LNs) removed during radical cystectomy (RC) for transitional cell carcinoma (TCC) of the bladder affects overall and disease-specific survival, but no consensus exists regarding the minimum number of LNs that should be removed. The goal of the current study was to determine if a threshold number of nodes exists, above which taking additional LNs has no clinical benefit. METHODS. A total of 1121 patients were identified who underwent RC for clinically localized TCC of the bladder between January 1990 and April 2004. To determine the relation of LNs removal and overall survival, a Cox proportional hazards model was used with pathologic stage, age, and comorbidity as covariates. A dose-response curve, adjusted for covariates, was modeled to assess the impact of an increasing number of LNs removed on overall survival. RESULTS. A median of 9 LNs were removed (range, 0-53 LNs). In multivariable analysis, all covariates (number of LNs removed, age, stage of disease, and comorbidity) were found to be predictive of survival. The dose-response curve for number of LNs versus survival revealed that, when adjusted for covariates, the probability of survival did not plateau but instead continued to rise as the number of LNs removed increased. CONCLUSIONS. No evidence was found that a minimum number of LNs is sufficient for optimizing bladder cancer outcomes when a limited or extended pelvic LN dissection is performed during RC. Instead, the probability of survival continues to rise as the number of LNs removed increases. This study supports a more extended LN dissection at the time of RC, and highlights the challenges of interpreting retrospective LN dissection data.