ObjectiveTo analyze the R0 resection rate and survival time of pancreatic cancer with serum IgG4 elevated, and to discuss whether serum IgG4 can distinguish autoimmune pancreatitis from pancreatic cancer.MethodsThe retrospective cohort study was adopted. The clinical data of 146 patients with pancreatic cancer confirmed by histology in Affiliated Hospital of Qingdao University from January 2016 to December 2019 were analyzed retrospectively. According to the level of serum IgG4, they were divided into normal IgG4 group (<1.35 g/L, n=124) and IgG4 elevated group (≥1.35 g/L, n=22). The tumor R0 resection rate, survival time and whether complicated with AIP of the two groups were compared.ResultsOne hundred and one patients (81.5%) with normal serum IgG4 underwent radical surgery, while only 13 patients (59.1%) with elevated serum IgG4 underwent radical surgery, the difference was significant (P=0.019). The median survival time of patients with normal serum IgG4 was 18.7 months, while patients with elevated serum IgG4 was 8.1 months, there was no significant difference between the two groups (P=0.121). Subgroup analysis showed that the median survival time of patients with pancreatic ductal adenocarcinoma in the normal IgG4 group was 17.5 months, while the IgG4 elevated group was 6.8 months, the difference was significant (P=0.016). Only 1 case of pancreatic cancer with AIP in the 2 groups.ConclusionsSerum IgG4 ≥1.35 g/L indicates low radical resection rate in pancreatic cancer and poor prognosis in pancreatic ductal adenocarcinoma. Serum IgG4 can only be used as an auxiliary index to distinguish pancreatic cancer from autoimmune pancreatitis.