The Limitations of Standard Clinicopathologic Features to Accurately Risk-Stratify Prognosis after Resection of Intrahepatic Cholangiocarcinoma.

BACKGROUND: The ability to provide accurate prognostic data after hepatectomy for intrahepatic cholangiocarcinoma (ICC) remains poor. We sought to develop and validate a nomogram to predict survival, as well as investigate the clinical implications of underestimating patients' risk of recurrence.

METHODS: Patients undergoing curative-intent resection of ICC between 1990 and 2015 at 14 major hepatobiliary centers were included. Variables significant on multivariable analysis were used to construct a nomogram to predict disease-free survival (DFS). The nomogram assigned a score to each variable included in the model and calculated the risk of recurrence.

RESULTS: Eight hundred ninety-seven patients are included in the analytic cohort. On multivariable Cox regression analysis, tumor size > 5 cm (HR 1.98, 95% CI 1.44-2.13; p < 0.001), multifocal ICC (HR 1.64, 95% CI 1.32-2.03; p < 0.001), lymph node metastasis (HR 1.63, 95% CI 1.25-2.11; p < 0.001), poorly differentiated tumor grade (HR 1.50, 95% CI 1.21-1.89; p < 0.001), and periductal infiltrating type (PI) morphology (HR 1.42, 95% CI 1.09-1.83; p = 0.008) were independent adverse risk factors associated with decreased DFS. The Harrell's c-index for the nomogram was 0.633 (with n = 5000 bootstrapping resamples) and the plot comparing predicted and actuarial DFS demonstrated a good calibration of the model. A subset of patients (n = 282) had a DFS worse than predicted (ΔPredicted DFS - Actuarial DFS > 6 months). Moreover, underestimation of a recurrence risk was more common among patients with clinicopathologic features traditionally considered "favorable."

CONCLUSION: A nomogram based on standard clinicopathologic characteristics was suboptimal in its ability to predict accurately risk of recurrence among patients with ICC after curative-intent liver resection. Particularly, the risk of underestimating patient risk of recurrence was highest among patients with historically favorable characteristics. Over one third of patients recurred > 6 months earlier than the DFS predicted by the nomogram.