Academy of Medical Sciences of I.R. Iran Archives of Iranian Medicine 1029-2977 29 1 2026 01 01 Risk factors of incidental cholangiocarcinoma in primary sclerosing cholangitis: A Cross-Sectional Study with ROC curve analysis 29 34 10.34172/aim.34922 EN Fardad Ejtehadi https://orcid.org/0000-0002-0791-0133 Saeid Hashemieh Ali Reza Safarpour https://orcid.org/0000-0002-9880-0043 Sara Shojaei-Zarghani https://orcid.org/0000-0001-8479-065X Salar Azadnik https://orcid.org/0000-0002-6825-5312 Alireza Shamsaeefar Nima Rahimikashkooli Journal Article 10.34172/aim.34922 2025 08 06 2025 12 24 Background: Cholangiocarcinoma (CCA) is the most common malignancy in patients with primary sclerosing cholangitis (PSC), which is typically associated with low survival rates due to late diagnosis. Objective: This study aimed to evaluate the predictors of incidental CCA in PSC patients. Methods: In this cross-sectional study, 425 patients aged 18 years or older who underwent liver transplant with a confirmed diagnosis of PSC were included. Demographic data, pre-transplant clinical features, and para-clinical evidence were obtained from medical records. Pathology experts examined livers removed during transplant, and CCA was diagnosed accordingly. Multivariable logistic regression and receiver operating characteristic (ROC) curve analyses were conducted to assess the risk factors for incidental CCA and the effectiveness of carbohydrate antigen 19-9 (CA 19-9) in predicting CCA, respectively. Results: Of the 425 included patients, 29 had PSC-CCA and 396 patients had PSC alone. According to the multivariable logistic model, CA 19-9 (odds ratio [OR] = 1.001, 95% confidence interval [CI]: 1.000-1.001, P-value= 0.041) and weight loss (OR= 4.712, 95% CI: 1.392 to 15.947, P-value= 0.013) were significantly associated with CCA development. ROC curve analysis also revealed that CA 19-9 could predict CCA (AUC = 0.737; 95% CI: 0.689-0.782) at an optimal cut-off point above 46 U/ml, with a good sensitivity (68%, bootstrapped 95% CI: 62-74%) and specificity (72.32%, bootstrapped 95% CI: 68-76%). Conclusion: We found that CA 19-9 and weight loss are independent predictors of incidental CCA in PSC patients, and a CA 19-9 level above 46 U/ml has relatively good predictive power for incidental CCA.