The diagnostic value of the foetoacinar pancreatic (FAP) protein in cancer of the pancreas; a comparative study with CA19/9.

The serum diagnostic value of the foeto-acinar pancreatic protein (FAP protein), an oncofoetal pancreatic antigen, was tested in 201 patients. Of these, 112 suffered from malignant disease (57 patients had pancreatic carcinoma and 55, extra-pancreatic malignancies) and 89 had benign disease (49 patients with hepato-pancreato-biliary disease and 40 with other benign disease). FAP protein was measured by a competitive radioimmunoassay. In this technique, the normal cut-off level was 10% inhibition. This was deducted from values in 32 normal sera. FAP protein levels superior to 10% inhibition were found in 86% of patients with pancreatic cancer, in 31% with non-pancreatic malignancy, in 69% with benign hepato-pancreato-biliary disease and in 20% with other benign diseases. Accordingly, sensitivity of FAP protein for pancreatic carcinoma was 86% and specificity, 66%. However, high FAP protein levels (greater than 30% inhibition) were almost exclusively seen in patients with pancreatic cancer. At this cut-off level, specificity increased to 95% but sensitivity decreased to 51%. Determination of the carbohydrate antigen CA19/9 was made in parallel by a commercially available assay. At the cut-off level of 37 u ml-1, CA19/9 in our serum panel had a sensitivity of 74% for pancreatic carcinoma and a specificity of 88%. In pancreatic cancer 55 out of 57 patients had elevated levels of either FAP protein or CA19/9 (sensitivity; 96%).