There are a number of reasons why CA19-9 is not part of a routine screening for the general population. First, it is not specific for pancreatic cancer. It can be elevated in a number of benign conditions related to inflammation. Some examples of benign, non-cancerous conditions that can have high CA19-9 levels are:
* Gallstones
* Biliary infection (cholangitis)
* Blockage of the bile duct (jaundice)
* Pancreatitis (swelling of the pancreas)
* Cystic fibrosis
* Liver disease
* Pulmonary Fibrosis
* Tuberculosis

Every test method can yield a false positive or a false negative result. False positives can cause anxiety in a patient until the result is ruled out/in.

Only the PDAC form of pancreatic cancer secretes CA19-9 except in approximately 10% of the Caucasian population who are non-secretors. They lack the genetic coding for the Lewis antigen associated with blood group factor also associated with the secretion of CA19-9. This makes it possible to have several other rare forms of pancreatic cancer go undetected.

There is the issue of cost to benefit of doing an annual mass screening for a cancer that in the US in 2023 will be diagnosed in approximately 64,050 cases out of an adult population of age 55 and older of 96,799,000 according to the 2020 US Census data (https://www2.census.gov/programs-surveys/demo/tables/age-and-sex/2020/older-population/2020older_table1.xlsx). Testing would have to be justified based on testing benefit over financial burden for taxpayer funding. An individual has the right to make the request for screening and if their private insurance doesn’t cover, can be paid out-of pocket.

For someone that has or had pancreatic cancer such as myself, the CA19-9 test is done multiple times a year even though I am 11 years out from initial diagnosis. For an individual that is deemed high risk as a result of having a genetic mutation associated with pancreatic cancer or a blood relative having been diagnosed, it makes sense to request early detection screening. In high risk individuals, a GI specialist may suggest other methods of surveillance that may include a scan or EUS.