CEA Tumor Markers

I had Stage II breast cancer 8 years ago.  I go for my checkups twice a year, more for my peace of mind than anything else.  Last summer I had a colonoscopy and the doctor removed two polyps.  The next month I went for my regular bi-annual checkup and my CEA was around 9; it had jumped from around 2.  She repeated the test for a couple of months and it didn't go down.  My oncologist then ordered a PET scan and it was fine.  By that time it had dropped to 4.7.   At my checkup in Jan it had gone back up to 6.  She repeated the PET scan and again it showed nothing.  My question is, could the colonoscopy have missed something?  Do all tumors show up on a PET scan?  Would CEA detect something before it could be read on a PET scan?  I know it is probably useless worrying, but as you know, you never get over the worry of cancer returning...

Leslie,

 In answer to your questions:

Could the colonoscopy have missed something?  Yes.

Do all tumors show up on a PET Scan? No.  Small ones won't show up.

Would CEA detect something before PET?  It might and it might not.  For some people CEA is not a good indicator, so PET might show it first.  For others it is a good indicator and it leads to getting a PET scan. 

Do you smoke?  Have you had any infections/inflammation? Both can lead to higher CEA's.  Women tend to have higher CEA's than men.

Given that it has been about 9 months since the first CEA and it has bounced around without treatment, I think you might be getting a false positive reading, but you should be diligent about monitoring things. Are you having another colonoscopy this summer? 

Jack