@wfs588wea, it's always concerning when lab tests are abnormal.
I like the information provided by the website Lab Tests Online (https://labtestsonline.org/) by the American Association for Clinical Chemistry (AACC). The information is trustworthy and easy to understand.

Here's the page about Cancer Antigen 19-9 (CA 19-9) https://www.testing.com/tests/cancer-antigen-19-9/
CA 19-9 is primarily used to monitor response to pancreatic cancer treatment and to watch for recurrence. In the section called "What does the test result mean?" it states:
"Levels of CA 19-9 that are initially high and then fall over time may indicate that the treatment is working and/or that the cancer was removed successfully during surgery. Levels that remain high or rise over time may indicate that treatment is not working and/or that the cancer is recurring."

It's important to remember that the CA 19-9 test is only one piece of the puzzle. Changes in levels may indicate when further investigation is needed. As @mcharlesfrancis mentioned, there are other things like inflammation or infection that can raise the levels.

How did the appointment with your wife's oncologist go? Was further testing ordered or further monitoring? How are you doing?