My father was diagnosed with colon cancer in August 2011.  The cancer was metastasized to liver (significant coverage on the liver).  He just finished his 7th round chemo treatment.  His Ca199 number has been reduced from 5900 to 90.  His ca724 initially was reduced to 60 and now is 270.  His latest CEA is 50.

I would like to ask for help to determine what is you opinion the reason(s) his ca724 is at 270.  Thanks.