MUC5AC and pancreatic ductal adenocarcinoma: These results are in agreement with findings that MUC5AC expression levels decreased as the malignancy of gallbladder tumor [24] and gastric signet ring cell carcinoma [25] increased; colon cancer negative for MUC5AC had more tumor recurrence, metastasis, and worse prognosis than those positive for MUC5AC [26]; and pancreatic ductal adenocarcinoma positive for MUC5AC expression was correlated with better prognosis [19] and less vascular invasion.