The tumour markers are a bloody mystery to me. About 5 years after my first BC I simply gave up getting tested. Even when I ended up with a whopping great recurrence they didn't show anything sinister. My current oncologist won't do it "No, no, they make everyone crazy, prove nothing' I concur.
Right through chemo he hasn't asked for that test--i know because I demand copies of all results. When I had my ovaries out the gyno wrote them up...Out of curiosity? Who knows, the results were low but none of that was helpful. I won't ask for that test until it comes back again and I have to think about what I do with mets.
This stuff can send you nuts, though it is very hard to ignore.