@denip - If you don't mind sharing, what was your husband's earliest and most recent CA 19.9 levels? Somewhat similar to your husband's situation, my CA 19.9 levels fell significantly, but began to rise prior to scheduled Whipple that has been twice postponed due to the current CA 19.9 levels. They slowly continue to rise. I'm now rescheduled for a Whipple in six weeks.
Continued success to you both in the shared struggles of beating back pancreatic cancer.