Seeking a standard for adequate pathologic lymph node staging in primary bladder carcinoma

The purposes of this study are to evaluate the adequacy of pathologic lymph node (LN) staging in radical cystectomy specimens from patients with urothelial carcinoma of the bladder and to analyze the frequency of LN metastases among different anatomic regions. All radical cystectomies performed for primary urothelial bladder cancer over a 5-year period (January 2007-September 2012) at a single institution were reviewed. Particular attention was paid to the total number of LNs examined, the number and location of LNs with metastases (positive LNs), and the presence or absence of extranodal tumor extension and/or lymphovascular invasion in the cystectomy specimen. Results and data were analyzed with Origin 6.0 and Microsoft Office Excel 2007 software. A total of 248 radical cystectomies with 8,432 LNs were reviewed. A total of 60 (24 %) cases, with 274 positive LNs out of the 1,982 total (13.8 %), were identified with a male to female ratio of 6.5:1 (52 male, 8 female patients). The average number of LNs examined in each case was 33.0 ± 20.9 (range 5-112). The average number of positive LNs identified in each case was 4.5 ± 4.8 (range 1-26). Among all of the LNs, the hypogastric/obturator (internal iliac) LNs were the most commonly submitted (35.2 %) and also yielded the highest number of positive LNs (46.0 %). On average, for cases staged pN1 and pN2, there was one positive LN per 17.8 and 8.9 LNs examined from the primary drainage LNs, respectively. For pN3 cases, one out of 4.4 secondary drainage LNs was found to be positive. Similarly, one out of 4.0 distant LNs was found to be positive in cases with pM1 staging. Our study suggests that, on average, 23 LNs (including 18 primary drainage LNs and five secondary drainage LNs) should be submitted for optimal pN staging. For adequate pM1 staging, an average of four distal LNs should be evaluated. In total, an average of 27 LNs (23 for pN staging and 4 for pM staging) should be examined in radical cystectomy specimens. We also propose to stratify the number of positive LNs according to the drainage area.