Pancreas cancer and CA-19/CEA

Hi, I am currently being treated for pancreas cancer with tumor on body an tail. While my CA-19 levels are dropping drastically with each treatment (currently ca-19 is at 171) my CEA numbers have been going up ( currently at 4.25). I understand smoking keeps it at higher level. What part does the CEA numbers play in my prognosis . And should I be concerned. Thxs!