The protocol at the hospital where I had chemo was not to test for CEA or have scans, until a few weeks after chemo had ended. The reason being, is that CEA can rise due to inflammation etc and therefore is not always a good indication of what is actually happening.
I happened to have a scan for an unrelated condition, halfway through chemo, which showed a nodule on the liver, so I started having CEA tests after that point. My CEA did rise during chemo, but went down after it ended. The nodule hasn't changed, so probably is benign.
If you look at my signature, you will see that my CEA rose from 1.2 to 4.6 during chemo. My onc considers 5.0 to be the upper limit for normal, so was not concerned about this (although at the time, I certainly was).
May 2015 right hemi CC cecum
removed terminal ileum, illeocecal valve, appendix, cecum, ascending colon, omentum
stage 3b T3 N1b MX 2/27 nodes (isolated tumour cells in 1 add'l node)
PNI - positive
LVI - positive
Folfox 12 sessions (oxi discontinued for 11 & 12)
Neulasta with 3-12 due to low WBC count
CEA at diagnosis 8.6
CEA after surgery 1.2
CEA during chemo 4.6 / 3.3 / 2.3
CEA after chemo 1.5 / 1.2 / 1.2 /1.2 /1.2 / 1.4 / 1.1 / 1.2 / 1.9 / 1.3 / 1.6 /1.4