Standard lymph node dissection for bladder cancer: significant variability in the number of reported lymph nodes

We compared the nodal yield after histopathological examination of extended bilateral pelvic lymph node dissection specimens for bladder cancer at 2 hospitals. Surgery at each hospital was done by the same 4 staff urologists using a standardized extended bilateral pelvic lymph node dissection template.

All consecutive patients with bladder cancer who underwent extended bilateral pelvic lymph node dissection from January 1, 2007 to December 31, 2009 were included in this study. Specimens were sent for pathological evaluation in a minimum of 2 packages per side. At the 2 pathology departments specimens were processed according to institutional protocols.

A total of 174 patients with a mean age of 62.7 years were included in analysis. At hospital 1 a mean of 16 lymph nodes were found after dissection vs a mean of 28 reported at hospital 2 (p <0.001). No significant differences were found in the number of tumor positive lymph nodes (p = 0.65). Mean lymph node density at hospitals 1 and 2 was 9.3% and 3.9%, respectively (p = 0.056).

Despite equal anatomical clearance by the same experienced surgeons we report a statistically significant difference between 2 pathology departments where the number of lymph nodes was evaluated after extended bilateral pelvic lymph node dissection for bladder cancer. Unless standardized methods are agreed on by pathologists, the number of reported lymph nodes as an indicator of surgical quality and lymph node density as a prognostic factor should be used cautiously.