Surgical Management of Intrahepatic Cholangiocarcinoma: Defining an Optimal Prognostic Lymph Node Stratification Schema.

Background: Metastatic disease to the regional lymph node (LN) is a strong predictor of worse long-term outcome after curative-intent resection of intrahepatic cholangiocarcinoma (ICC). The objectives of this study were to assess the prognostic performance of American Joint Committee on Cancer (AJCC)/International Union Against Cancer, 7th edition, N stage, LN ratio (LNR), and log odds of metastatic LN (LODDS) staging criteria in patients with ICC.

Methods: The surveillance, epidemiology, and end results cancer registry was queried to identify 749 patients who underwent surgical resection of ICC during 1988-2011. The Kaplan-Meier method and Cox proportional hazards regression models were used to analyze survival. The relative discriminative abilities of the different LN staging systems were assessed by the Harrell concordance index (c statistic).

Results: Of the 749 patients, 477 (63.7 %) had no LN metastasis, while 272 (36.3 %) had LN metastasis. Patients with LN metastasis had an increased risk of death (hazard ratio 2.42, 95 % confidence interval 1.98-2.95; P < 0.001). When assessed using categorical values, LNR (C index 0.620) and LODDS (C index = 0.630) showed a better prognostic performance than the AJCC 7th edition staging system (C index = 0.607). When assessed using continuous values, the LODDS staging system (C index = 0.626) slightly outperformed LNR (C index = 0.621). There was heterogeneity of outcomes among patients with no LN involved (LNR = 0) or all LN involved (LNR = 1), indicating that LODDS may better characterize and stratify outcomes among these groups.

Conclusions: LODDS and LNR showed better prognostic performance than the AJCC 7th edition staging system. When assessed as categorical and continuous variables, LODDS outperformed LNR, especially among those patients with either very low or high LNR.