CA19-9 is generally considered as a marker for tumours originating from the pancreas and bile duct, although it can also arise from other organs such as the gallbladder, stomach, colon, lung, breast and gynaecological structures.
In approximately 5% of the normal population, CA19-9 is elevated marginally. People with bile duct obstructions or pancreatitis may also have elevated CA19-9 until treatment is given.
If your CA19-9 level is only marginally elevated and has been this way for years without escalating and you are perfectly well, chances are you will be fine. All you have to do is to watch the level periodically. However, if the level is clearly moving up over a short period of time or you have risk factors for pancreas or bile duct problem or you are not feeling so well lately, consider seeking help from your digestive specialist to exclude any major issues.
Most doctors do not recommend routine, indiscreet cancer screening with serum CA19-9 as it is non-specific and may lead to unnecessary and often expansive tests. Do consult your doctor on your options in the follow-up plan moving forward.