Adequate Lymph Node Assessment for Extrahepatic Bile Duct Adenocarcinoma

Objective: To examine the importance of adequate lymph node sampling in staging of extrahepatic bile duct cancer (EHBDCA). Summary of Background Data: The American Joint Committee on Cancer staging manual (sixth edition) states that histologic examination of at least 3 lymph nodes is required for adequate N stage determination for EHBDCA. This recommendation has not been validated; however, there has been no comparative assessment of the proximal versus distal bile duct cancer. Methods: A total of 257 patients (144 hilar cholangiocarcinoma [HCCA] and 113 distal bile duct adenocarcinoma [DBDCA]) who underwent curative intent resection (1987-2007) were analyzed; patients with gallbladder cancer were excluded. Final disease staging, including lymph node status and total number of nodes examined (total lymph node count), was obtained from the final pathology report. Differences in disease-specific survival, according to nodal status, were compared using the log-rank test. R1 resections (n = 51) were excluded from this analysis. Results: Metastasis to regional lymph nodes was noted in 89 patients (34.6%) and was an independent prognostic factor of poor survival (median disease-specific survival N0 vs. N1: 53.5 vs. 19.3 months, P < 0.0001, hazard ratio = 2.1 [95% CI: 1.4-3.2]). The median total lymph node count was 6 (range: 0-42), and was significantly lower for HCCA compared with DBDCA (median = 3 [range: 0-16] vs. 12 [range: 1-42], P < 0.001, respectively). For the entire cohort, patients who underwent R0 resection and were classified as N0, based on total lymph node count <11, had a disease-specific survival that was significantly worse than that of patients classified as N0 based on total lymph node count >= 11 (52.6 +/- 9.8 months vs. not reached, P = 0.008). The estimated optimal total lymph node count for HCCA differed from that of DBDCA (n = 7 vs. n = 11, respectively). Conclusions: Adequate lymph nodes assessment of EHBDCA, based on the current AJCC recommendations, results in understaging of these tumors. With respect to the optimal total lymph node count, HCCA, and DBDCA should be considered separately.