What can this mean . before chemotherapy cea was 65, after 1 round 80 and after 2 round 55 for metastic colon cancer ?

CEA LEVEL: CEA LEVEL is a good marker for response to treatment for colon cancer. Follow up with your doctor to update CT/PET SCAN and continue to monitor CEA LEVEL. The lower it gets the better . Other things can raise the CEA level as well ie smoking. Make sure to follow up as scheduled with repeat CT scans

CEA: In general, rise in CEA in patients with metastatic colon cancer represents the disease progression. However, CEA surge phenomena was also described in patients who responded to the initial intensive chemotherapy. Immediate rise in CEA is usually not related to the disease progression. CEA surge is defined by >20% increase from its baseline.

Units?: Given that u r from England, the units for the CEA test may be different there. In the US, a level less than 5 ng/mL is "normal". CEA is used as a tumor marker (i.e., colon cancer likely), but (to my knowledge) is not very useful as an indicator of response to treatment. U describe incomplete treatment, anyways. After finishing the rounds of chemotherapy, then check the CEA- that may b useful.