Combination of Serum CA 19-9 and Endoscopic Ultrasound Findings Can Predict Malignancy Risk in Patients With Chronic Pancreatitis Presenting With Pancreatic Head Mass: A Proof-of-Concept Study.

ABSTRACT

BACKGROUND AND AIMS: Inflammatory head mass of pancreas (IMP) developing in background of chronic pancreatitis (CP) is difficult to distinguish from carcinoma pancreas. We aimed to delineate natural course of IMP and predict their malignancy risk, avoiding unnecessary biopsies. MATERIALS AND METHODS: In this retrospective single-center study, clinical records of patients with CP with diagnosed pancreatic head mass were reviewed. Clinical, laboratory, imaging, endoscopic findings, and follow-up details were retrieved from prospectively maintained database. A diagnostic nomogram was developed combining serum cancer antigen 19-9 and endoscopic ultrasound (EUS) findings to predict the risk of malignancy. RESULTS: We identified 107 patients with pancreatic head mass with CP of whom 87 (81.3%) were IMP and 20 (18.7%) were malignant. Patients with IMP were more frequently young males with alcohol-related CP and low CA 19-9 in comparison with those with malignancy (age IMP 41.3 ± 11.3 vs carcinoma 49.3 ± 14.5 years [ P = 0.009]; males 89.7% vs 65% [ P = 0.011]; alcoholic etiology 71.3% vs 20% [ P < 0.001]; median CA 19-9 25.78 [interquartile range, 7.20-120.60] vs 1034.50 [106.65-7808.25] [ P < 0.001]). A diagnostic nomogram combining CA 19-9 and EUS findings could identify malignancy with an optimism-corrected c-statistic of 0.905, which was better than both CA 19-9 (0.80) and EUS alone (0.826). Patients with IMP had relatively benign disease course with 40.2% biliary obstruction, 20.7% portal venous thrombosis, 14.9% gastric outlet obstruction, and 1-, 3-, and 5-year survival being 97.3%, 92.7%, and 92.0%, respectively. Surgery was required in only 12 patients (13.8%) with IMP. CONCLUSIONS: Combination of CA 19-9 and EUS best identifies malignancy risk in patients with IMP, who have otherwise benign course.