How does the CA 19-9 marker help diagnose pancreatic cancer?

If you are diagnosed with pancreatic cancer, your physician may use changes in your CA 19-9 levels to determine if your tumor is remaining stable, progressing, or responding to treatment. Your doctor may take a baseline CA 19-9 level before surgery or before beginning a cycle of chemotherapy. If your CA 19-9 levels decrease after treatment, that typically indicates a positive response. If after several cycles of chemotherapy your CA 19-9 levels remain the same, that indicates your cancer is stable. If, however, your CA 19-9 levels rise, that can indicate either a recurrence of your cancer or that you are no longer responding to your current treatment plan.