A tumor marker Ca 19-9 in diabetics can lead to misdiagnosis of pancreatic cancer

Diabetes is increasing all over the world along with the increase of obesity and associated diseases and is a well-known risk factor for pancreatic cancer. The incidence of pancreatic cancer is also increasing and has one of the lowest survival rates of all cancers.

CA 19-9 is a tumor-associated antigen which is elevated in pancreatic cancers, cancers of the upper gastrointestinal tract, ovarian cancer, hepatocellular cancer, colorectal cancer, inflammatory conditions of the hepatobiliary system, and in thyroid diseases.

CA 19-9 is used in the diagnosis of pancreatic cancer but is also a marker of pancreatic tissue damage which might be caused by diabetes. The association between diabetes, pancreatic cancer and elevated levels of Ca 19-9 has not been investigated until now.

A research article published in October 28 issue of the World Journal of Gastroenterology addresses this association. The research group led by Dr Oya Uygur-Bayramicli from Istanbul examined 76 type 2 diabetics and matched them with control subjects of the same age and gender in order to get reliable comparisons. Ca 19-9 levels were statistically significantly higher in the diabetic group but there was not any case of pancreatic cancer in that group, which was confirmed with the help of abdominal CT.

One conclusion reported by the researchers is that diabetes can be accepted as the last step of chronic pancreatitis with the new developing concepts of pathogenesis and that the elevation of Ca 19-9 is due to chronic pancreatitis and not to pancreatic cancer.

As a solution to the problem they suggest using higher cut-off values of Ca 19-9 in diabetic patients to differentiate benign and malignant pancreatic disease. Furthermore, subtle elevations of CA 19-9 in diabetics should be considered an indication of exocrine pancreatic dysfunction.

The study was performed in a large teaching hospital in Istanbul, Turkey, with a special interest in diabetes and gastrointestinal oncology and is therefore quite representative of the population.