Proposed cut-off value of CA19-9 for detecting pancreatic cancer in patients with diabetes: a case-control study

Pancreatic cancer is a highly lethal malignancy. CA19-9 is a well-known marker for diagnosis of pancreatic cancer, but the serum CA19-9 level is reported to be elevated in patients with poorly controlled diabetes. This study evaluated the sensitivity, specificity, and cut-off value of serum CA19-9 for detection of pancreatic cancer in patients with diabetes. A case-control study of 236 patients was performed. The case group was selected from diabetic patients with pancreatic cancer, while one control was selected for each case from among diabetic patients without pancreatic cancer during the same period. The case group (n = 118) and the control group (n = 118) were matched for age, sex, and pancreatic cancer risk factors. Receiver operating characteristic (ROC) curves were plotted to determine the serum CA19-9 level that predicted pancreatic cancer. Then the sensitivity and specificity of CA19-9 were calculated for the threshold value. There were no significant differences of age, sex, BMI, smoking, alcohol intake, and HbA1c between the case and control groups. According to ROC analysis, a serum CA19-9 level of 75 U/mL had the maximum sensitivity and specificity for separating diabetic patients with or without pancreatic cancer. Using this cut-off value, the sensitivity and specificity of CA19-9 for pancreatic cancer was 69.5% and 98.2%, respectively, while the area under the ROC curve was 0.875 [95%CI: 0.826–0.924]. We propose that a serum CA19-9 level of 75 U/mL should be used as the cut-off value when screening patients with diabetes for pancreatic cancer.