Ca 19-9
Cancer antigen 19-9 (CA 19-9) is a protein that exists on the surface of certain cancer cells. CA 19-9 does not cause cancer; rather, it is shed by the tumor cells, making it useful as a tumor marker to follow the course of the cancer. CA 19-9 is elevated in 70% to 95% of people with advanced pancreatic cancer, but it may also be elevated in other cancers, conditions, and diseases such as colorectal cancer, lung cancer, gallbladder cancer, bile duct obstruction (e.g., gallstones), pancreatitis, cystic fibrosis, and liver disease. Small amounts of CA 19-9 are present in the blood of healthy people.