A greater number of dissected lymph nodes is associated with more favorable outcomes in bladder cancer treated by radical cystectomy: a meta-analysis

The optimal extent of lymph node dissection (LND) is currently not established, and the debate regarding the association between the number of dissected nodes and the outcomes of bladder cancer treated by radical cystectomy (RC) is still ongoing. Therefore, the present meta-analysis was performed to clarify this potential relationship. Eligible studies were retrieved via an electronic search for studies published up to April 2016, and by manual review of the references. A total of 25 cohort studies involving 41,400 bladder cancer patients who underwent RC were included. The summary relative risk estimates (SRRE) based on the highest compared with the lowest categories of LND were estimated by variance-based meta-analysis. Heterogeneity among the study results was explored through stratified analyses. Overall, bladder cancer patients with the highest category of LND had 28%, 34% and 36% reduced risks, corresponding to overall survival (SRRE = 0.72; 95% CI, 0.64-0.80), cancer specific survival (SRRE = 0.66; 95% CI, 0.54-0.80) and recurrence-free survival (SRRE = 0.64; 95% CI, 0.50-0.82), respectively, compared with patients with the lowest category of LND. In summary, the patients with a greater number of dissected lymph nodes had statistically significant survival advantages in terms of the outcomes of bladder cancer following RC. The number of dissected lymph nodes could be an independent prognostic factor for bladder cancer. These findings need to be validated in prospective and larger epidemiological studies with a longer follow-up period.