Thank you Colleen for the link to the CA19-9. It was very helpful for understanding just what meaning it has. I asked my doctor about this number, and he said it is just one of several tests/measurements they use to determine the progress of treatments. Unfortunately, after 5 months of treatment ( 4 treatments of Folfirinox and 8 with Gemzar/ abraxane) my tumor has not shrunk. My doctor said he was not disappointed with that but felt the decrease in CA-19-9 was good new.......I certainly hope so!