Lymph node density vs. the American Joint Committee on Cancer TNM nodal staging system in node-positive bladder cancer in patients undergoing extended or super-extended pelvic lymphadenectomy

Purpose We compared the prognostic value of the American Joint Committee on Cancer (AJCC) TNM nodal staging system with that of lymph node (LN) density in patients with LN-positive bladder cancer who received extended or super-extended pelvic lymphadenectomy. Methods Of the 1,018 patients, who underwent radical cystectomy and pelvic lymphadenectomy between February 2005 and August 2014, 110 patients with LN metastases with extended (n = 68) or super-extended (n = 42) pelvic lymphadenectomy were included. All patients were staged using the 2002 (sixth edition) and 2010 (seventh edition) AJCC TNM staging systems. The association of several variables with recurrence-free survival (RFS) and overall survival (OS) was evaluated. Results The median number of total LNs removed was 29 (6–118) and the median LN density was 12.5% (1.6%–100%). RFS and OS were not significantly different between the 2002 (pN1-pM1) and 2010 (pN1-N3) AJCC TNM nodal staging systems (sixth edition: P = 0.512 and P = 0.519; seventh edition: P = 0.676 and P = 0.671, respectively). The 2-year RFS and OS rates according to the LN density quartiles were 58.5% and 76.9% in Q1, 39.1% and 70.8% in Q2, 28.8% and 50.1% in Q3, and 12.7% and 20.8% in Q4 (P = 0.001 and P = 0.001, respectively). Multivariate analysis adjusted for the 2010 AJCC TNM staging system showed that LN density was associated with a decreased OS (HR = 1.024; 95% CI: 1.010–1.039; P = 0.001). The nodal staging system (2002 or 2010) was not associated with the RFS and OS. Conclusions LN density shows a better prognostic value than the AJCC TNM nodal staging system in patients with LN-positive bladder cancer receiving extended or super-extended pelvic lymphadenectomy.