@peterello
Here's a plot of the 2025 data from CT scan in April (NED) to first routine CT scan (Jul 18) which occurred with metastatic recurrence on the CT scan. Our Oncology team relies more heavily on the CT scan for definitive diagnosis. This plot includes the most recent point showing an apparent acceleration in the rate of increase in CA19-9 values. We moved the CT scan to early next week and we expect to see tumor regrowth requiring a change in treatment. The small "upticks" were in the range of 1 to 10 units and tended to bounce around with no clear direction as opposed to the later data all of which were directionally increasing. As I mentioned, in our case, the trend lines were more important than any single data point. As to why the upper normal limit is 54, I have no direct knowledge of how that specific number was selected but it is the system used at the Fred Hutch Cancer Center in Seattle - I have to trust their calibration! :>)