Abstract: Objective：To investigate the characteristics and related influence factors of lymph node metastases in patients undergoing radical cystectomy and lymph node dissection for bladder cancer. Methods: The data of 522 patients who underwent radical cystectomy and pelvic lymph node dissection at Department of Urology, Peking University First Hospital from 1998 to 2012, were retrospectively collected, and the lymph node mapping was performed in all the patients to determine the location of metastatic lymph nodes.Results: For the 522 patients with bladder cancer, lymph node metastasis occurred in 99 patients, and the incidence of lymph node metastasis was 19.0%. The incidence at different tumor stages was: 3.7% in T1 (6/164), 10.5% in T2 (17/160), 36.7% in T3(40/107), and 41.9% in T4 (36/86). The most common involved lymph nodes were hypogastric/obturator lymph nodes (77/99, 77.8%) and external iliac lymph nodes (35/99, 35.4%). The mean number of lymph nodes dissected was 11.6 (1-51). The lymph node density (number of lymph nodes involved/number of lymph nodes removed) was 44.1%. The incidence of lymph node metastasis was statistical related to tumor stage (P<0.01,OR 2.71,95% CI 2.13-3.44) and tumor grade (P<0.01,OR 3.81,95% CI 1.66-8.74), while age, gender, smoke history, and weight had no statistical significance. Conclusion:Lymph node metastasis is the most common metastasis route of bladder cancer. The incidence of lymph node tumor involvement is correlated with increasing tumor stage and tumor grade. The most common involved lymph nodes are hypogastric/obturator lymph nodes and external iliac lymph nodes. Radical cystectomy and bilateral pelvic lymph nodes dissection are of great significance in the treatment of bladder cancer.

Key words: Urinary bladder neoplasms, Neoplasm metastasis, Lymph nodes, Cystectomy