Recommended Minimal Number of Harvested Lymph Nodes for Intrahepatic Cholangiocarcinoma

BACKGROUND Lymph node (LN) metastasis is one factor indicating a poor prognosis after radical surgery for intrahepatic cholangiocarcinoma (ICC). Although several guidelines have recommended that LN dissection be strongly considered at the time of ICC surgery, no clear evidence regarding the appropriate number of harvested LNs has been established. Thus, we aimed to identify the minimum number of harvested LNs required for ICC by using a Bayesian Weibull model. METHODS Data from 142 patients who underwent radical hepatectomy (R0) for ICC from January 2000 to December 2018 were retrospectively reviewed. A Bayesian Weibull model was developed to analyze the effect of number of harvested LNs on survival of patients without (N0; n = 71) and with (N1; n = 71) metastatic nodes. We also compared the percentage of N1 patients (i.e., the N1 rate) in each of the five subgroups categorized according to the number of harvested LNs (1-4, 5-8, 9-12, 13-16, and ≥ 17). RESULTS In patients with 5 or more harvested LNs, the hazard ratio (HR) for LN metastasis was above the reference line (the HR with 5 harvested LNs, 1.95 (1.09-3.45)). The N1 rate of the 1-4 harvested LNs subgroup was lower than that of the other subgroups (e.g., 1-4 vs. 5-8; 16.1% vs. 39.4%, p = 0.014). CONCLUSION Our results suggest that at least 5 LNs should be harvested in patients who undergo radical surgery for ICC to promote accurate staging.