Association between the number of dissected lymph nodes during pelvic lymphadenectomy and cancer-specific survival in patients with lymph node-negative urothelial carcinoma of the bladder undergoing radical cystectomy

Background. A larger number of dissected lymph nodes (LN) during pelvic lymphadenectomy in patients with muscle-invasive transitional-cell carcinoma of the bladder treated by radical cystectomy (RC) is crucial for exact tumor staging and is associated with a positive oncological outcome. Methods. Clinical and pathological records of 1291 patients undergoing RC due to LN-negative transitionalcell carcinoma of the bladder were summarized and evaluated in a multi-institutional database. The number of removed LNs and the presence or absence of lymphovascular invasion were assessed. On the basis of multivariate Cox regression analyses, a threshold number of removed LNs was defined that exerted an independent influence on cancer-specific survival (CSS). Results. In multivariate Cox regression models for different numbers of removed LNs, a statistically significant enhancement of CSS could be demonstrated for a LN count of 16. Furthermore, the integration of the dichotomized LN count of 16 resulted in a statistically significantly enhanced predictive ability of the model for CSS. Patients with<16 and ≥ 16 removed LNs showed CSS rates after 5 years of 72% and 83%, respectively (P = 0.01). In addition, age, sex, pT stage, and lymphovascular invasion had independent influences on CSS in every Cox regression model. Conclusions. In patients undergoing RC, removal of a higher LN count is associated with an improved oncological outcome. The information resulting from an assessment of lymphovascular invasion and an extended lymphadenectomy is critical for stratification of risk groups and identification of patients who might benefit from adjuvant treatment.