Why do I need a CA 19-9 test?You may need a CA 19-9 blood test if you've been diagnosed with pancreatic cancer or other type of cancer related to high levels of CA 19-9. These cancers include bile duct cancer, colon cancer, and stomach cancer.Your health care provider may test you on a regular basis to see if your cancer treatment is working. You may also be tested after your treatment is complete to see if the cancer has come back.
