Serum carcinoembryonic antigen improves accuracy in differentiating autoimmune pancreatitis from early-stage pancreatic cancer

Background and aims: Autoimmune pancreatitis (AIP) is an IgG4-related disease that is prone to be misdiagnosed as pancreatic cancer (PC) because of similar clinical symptoms and imaging appearance. Serum IgG4 has helped much in the differentiation of the two diseases, but its diagnostic sensitivity and specificity are still not very satisfactory. Methods: In this work, 82 AIP and 160 stage IA and IB PC patients with complete clinical and laboratory data were enrolled and analyzed retrospectively. Serum IgG4, CA19-9, CEA and total bilirubin levels were measured. Mann-Whitney U and Chi-square test were used for statistical analyses, and receiver operating characteristic curve analysis was performed to determine optimal cut-off values and the area under the curve. Results: IgG4 was the best single serum marker, while either serum CA19-9 or CEA alone also help to differentiate AIP and early-stage PC patients. Combination of CA19-9 improved the overall diagnostic efficiency of IgG4 but sacrificed the sensitivity a little. Further incorporation of serum CEA into the combination of IgG4 and CA19-9 in a special pattern, however, produced the best diagnostic performance with intriguing parameters: sensitivity, 86.59%; specificity, 95.63%; positive predictive value, 91.03%; negative predictive value, 93.29%: accuracy, 91.03%; and AUC, 0.911. Conclusions: This article, for the first time, revealed that CEA, in combination with serum CA19-9 and IgG4 in a special pattern, would overwhelmingly enhance the diagnostic performance of serum IgG4 alone or the combination of IgG4 and CA19-9 in differentiating AIP from early-stage PC patients. The new utility of CEA is worthy of further clinical investigation.