Clinical significance of CA 19-9 elevation during postoperative surveillance for extrahepatic bile duct cancer: a nomogram-based approach for the prediction of short-term recurrence

Background: This study aimed to assess the significance of elevated carbohydrate antigen (CA) 19-9 in postoperative surveillance of extrahepatic bile duct cancer and to identify short-term recurrence predictors. Methods: This retrospective study included patients with elevated CA 19-9 post-curative surgery. Patients were categorized into positive and negative CT groups based on the detection of recurrence at CA 19-9 elevation. Short-term recurrence was defined as recurrence within 6 months in the negative CT group. We identified the factors associated with short-term recurrence and devised a predictive nomogram. Results: Among the 190 patients, 91 (47.9 %) exhibited tumor recurrence with CA 19-9 elevation (CT-positive group), whereas 99 (52.1 %) showed no recurrence (CT-negative group). In the CT-negative group (n = 99), 22 (22.2 %) experienced short-term tumor recurrence within 6 months. Preoperative CA 19-9 (odds ratio [OR]: 1.5, p = 0.016), postoperative CA 19-9 (OR: 1.9, p = 0.047), adjuvant treatment (OR: 3.5, p = 0.032), and the absence of inflammation (OR: 3.5, p = 0.045) were predictors of short-term recurrence. The area under the curve of the nomogram was 0.80 (95 % CI: 0.69–0.90). Conclusion: Despite elevated CA 19-9 levels, approximately 50 % of patients exhibited no recurrence during postoperative surveillance for extrahepatic bile duct cancer. Factors influencing short-term recurrence encompass pre- and postoperative CA 19-9, adjuvant treatment, and inflammatory status.