A novel prognostic system combining carbonic anhydrase II and preoperative CA19-9 for intrahepatic cholangiocarcinoma after curative resection.

BACKGROUND: The role of carbonic anhydrase II (CAII) in intrahepatic cholangiocarcinoma (ICC) was investigated and a novel prognostic system combining CAII and preoperative carbohydrate antigen 19-9 (CA19-9) was established to predict the survival of patients with ICC after curative resection. METHODS: A total of 110 patients who underwent curative-intent resection for ICC between 2012 and 2020 were retrospectively analyzed. CAII in tumor and peritumor regions was examined by immunohistochemistry, and the relationships between clinicopathological factors and the prognostic value of CAII and CA19-9 were analyzed. RESULTS: CAII was frequently downregulated in ICC tissues (p < .001). Multivariate analyses indicated that showed that both low CAII expression level and preoperative CA19-9 ≥236 U/ml were independent risk factors for overall survival (OS) and recurrence-free survival (RFS) in patients with ICC after radical resection. Survival analysis revealed that patients with high CAII and low CA19-9 were significantly associated with a better OS and RFS (p < .001). The time-dependent receiver operating characteristic curves showed that CAII + CA19-9 had better prognostic predictive ability than CAII or CA19-9 alone. The nomogram constructed on independent factors including T stage, lymph node metastasis, CA19-9 (continuous variable), and CAII achieved C-indexes of 0.754 (95% CI, 0.701-0.807) and 0.730 (0.674-0.785) for OS and RFS, respectively. The calibration curve revealed acceptable agreement between actual and predicted OS and RFS. CONCLUSIONS: The combination of CAII and preoperative CA19-9 is a novel and useful prognostic tool for predicting the survival of patients with ICC after curative resection and guiding clinical decisions. PLAIN LANGUAGE SUMMARY: Carbonic anhydrase II (CAII) was frequently downregulated in intrahepatic cholangiocarcinoma (ICC) tissues. Survival analysis revealed that CAII is a novel independent factor for prognosis in patients with ICC after curative resection. CAII could be a useful prognostic marker for patients with ICC after surgery. The combination of CAII and preoperative carbohydrate antigen 19-9 is a novel and useful prognostic tool for predicting the survival of patients with ICC after curative resection and guiding clinical decisions.