Pancreatic cancer: oncologist says ca19-9 blood tests are showing false negative (<37)results. how does he know for sure there is cancer?

More information: Hi. To me, that looks like very good information (the tumor marker is undetectable). If he has information otherwise, he needs to explain it to you. Was your CA 19-9 elevated before surgery, chemo + radiation? If so, and it's negative now, based on the information available, I'd say that's exactly the result you'd like to see! Ask him to explain his position. Good luck!

Pancreatic cancer: The only way to know for sure is with a tissue diagnosis from a biopsy. Best of luck.

Understanding labs: This isn't a "false negative" -- a great many pancreatic cancers simply don't make CA19-9. There may also be too little cancer left to make enough to be meaningful. This is just one of many examples of how limited tumor markers are. I trust the oncologist has his/her reasons for believing cancer is present. You'll need to ask. Best wishes.