Developing a Prognostic Model for Intrahepatic Cholangiocarcinoma Patients With Elevated Preoperative Carbohydrate Antigen 19-9 Levels: Volume-Adjusted CA19-9 (VACA) as a Novel Biomarker.

Abstract

Purpose: The predictive sensitivity of carbohydrate antigen 19-9 (CA19-9) in assessing the prognosis of intrahepatic cholangiocarcinoma (ICC) remains inadequate. Integrating CA19-9 with tumor volume offers a potentially viable strategy for improving prognostic accuracy. This study aimed to develop a prognostic model utilizing volume-adjusted CA19-9 (VACA) for ICC patients.

Patients and methods: A retrospective analysis was conducted on data from 436 ICC patients. These patients from two centers were divided into the training (n = 291, Center 1) and validation (n = 145, Center 2) cohorts. Using the training cohort, univariate and multivariable Cox regression analyses were employed to identify clinicopathological characteristics significantly associated with overall survival (OS) and recurrence-free survival (RFS), which enabled the construction of prognostic nomograms both with and without VACA. The nomograms' discriminatory and calibration abilities were assessed using receiver operating characteristic (ROC) curves, decision curve analysis (DCA) curves, and calibration curves, applying both training and validation cohorts.

Results: VACA emerged as an independent variable that significantly correlated with prognosis. The nomogram incorporating VACA demonstrated superior accuracy in predicting OS and RFS rates compared to the model without VACA. In the validation cohort, the nomogram with VACA yielded area under the ROC curve (AUC) values of 0.695 (95% CI = 0.597∼0.793) and 0.666 (95% CI = 0.559∼0.773) (1- year), 0.662 (95% CI = 0.518∼0.806) and 0.651 (95% CI = 0.446∼0.857) (3- years), and 0.701 (95% CI = 0.486∼0.916) and 0.703 (95% CI = 0.428∼0.978) (5- years) for OS and RFS, respectively, along with improved calibration and DCA curves.

Conclusions: VACA, formed by integrating tumor volume with CA19-9, exhibits promising prognostic capabilities. The nomogram incorporating data from two centers and utilizing VACA demonstrates robust prognostic performance and holds clinical utility.

Condensed abstract: Combining CA19-9 with tumor volume presents a potentially viable strategy for improving prognostic accuracy. The nomogram incorporating VACA demonstrates robust prognostic performance and holds clinical utility.