Objective: To analyze lymph node status in resected perihilar cholangiocarcinoma, to clarify which index (ie, location, number, or ratio of involved nodes) is better for staging, and to determine the minimum requirements for node examination.
Background: In the TNM classification for perihilar cholangiocarcinoma, the number or ratio of involved nodes is not considered for nodal staging. The minimum requirement for histologic examination of lymph nodes is arbitrary.
Methods: This study involved 320 patients with perihilar cholangiocarcinoma who underwent resection from January 2000 to December 2009 at Nagoya University Hospital. The relationship between lymph node status and patient survival was retrospectively analyzed.
Results: Total lymph node counts (TLNCs), ie, the number of lymph nodes examined histologically, averaged 12.9 ± 8.3 (range: 1-59). Lymph node metastasis was found in 146 (45.6%) patients and was an independent, powerful prognostic factor. The survival rates were not significantly different between patients with regional node metastasis alone and those with distant node metastasis (19.2% vs 11.5% at 5 years, P = 0.058). The survival for patients with multiple node metastases was significantly worse than that for patients with single metastasis (12.1% vs 27.6% at 5 years, P = 0.002), regardless of the presence or absence of distant lymph node metastasis. The survival for patients with lymph node ratios (LNRs) of 0.2 or less was significantly better than that for patients with LNRs greater than 0.2 (21.4% vs 13.5% at 5 years, P = 0.032). Upon multivariate analysis of the 146 patients with lymph node metastasis, the number of involved nodes (single vs multiple) was identified as an independent prognostic factor (RR of 1.61, P = 0.045), whereas the locations (regional alone vs distant) and ratios (LNR ≤ 0.2 vs LNR > 0.2) of involved nodes were not. When the 148 pN0-R0 patients were divided into 3 groups (ie, those with TLNC ≥ 8, with TLNC = 5, 6, or 7, and with TLNC ≤ 4), survivals were identical between the first and second groups, whereas they were largely different between the former two and the third.
Conclusions: Lymph node metastasis is a powerful, independent prognostic factor in perihilar cholangiocarcinoma and is better classified based not on location but on the number of involved nodes. To adequately assess nodal status, histologic examination of 5 or more nodes is recommended.