Prognostic Accuracy of the Seventh Edition of the TNM Classification Compared with the Fifth and Sixth Edition for Distal Cholangiocarcinoma

Background: The TNM classification for distal cholangiocarcinoma was first introduced in the 7th edition, which was published in 2009; however, prognostic accuracy compared with the 5th and 6th editions has not yet been evaluated and requires validation.

Methods: A prospective histological database of patients with distal bile duct cancer was analyzed, and histological parameters and stage of the distal cholangiocarcinoma were assessed according to the 5th, 6th, and 7th editions of the TNM classification.

Results: Between 1994 and 2012, a total of 516 patients underwent pancreatic head resection, of whom 59 patients (11.4 %) experienced histologically confirmed distal cholangiocarcinoma. The median overall survival time was 22.2 months (13.1-31.4). Tumor recurrence occurred in 23 patients after a median disease-free survival time of 14.1 months. The 7th edition showed a monotonicity of all gradients, with a stepwise increase of mortality related to a stepwise increase of tumor stage (log-rank test; p < 0.05) demonstrating best discrimination of all tested editions [area under the receiver operating characteristic curve (AUC) 0.82; 95 % CI 0.70-0.95; p = 0.012]. The discrimination rate was low for the 5th (AUC 0.67; 95 % CI 0.42-0.91; p = 0.18) and 6th editions (AUC 0.70; 95 % CI 0.47-0.93; p = 0.11), while the log-rank test did not reach statistical significance. On multivariate analysis, lymph node involvement and positive resection margins were positive and independent predictors of inferior survival (p < 0.05).

Conclusions: The 7th edition of the TNM classification was favorable in terms of predicting outcome, and generated a monotonicity of all grades. Strikingly, the 7th edition, but not the 5th and 6th editions, was of prognostic significance to predict outcome.