High CA 19 9
A raised CA 19 9 level can be associated with gastrointestinal cancers, especially pancreatic cancer. Tumour markers are not cancer specific and may also be elevated in benign conditions (for example, biliary obstruction or inflammation). Therefore, high CA 19 9 cannot diagnose cancer and is mainly useful in monitoring known malignancy, not screening or early detection.
Low or Normal CA 19 9
A normal CA 19 9 does not rule out cancer, because tumour markers may remain normal in early stage disease or even in some advanced cancers. Tumour markers have limited sensitivity, so low values cannot be used to exclude malignancy.
