Hello @shireen71 and welcome to Mayo connect. These numbers cause so much distress, I am sorry for that. They do tend to fluctuate, my doctor does not even test them regularly anymore. He says they aren’t really reliable enough to be helpful.
There is another conversation here on connect about this topic, from about a year ago. Here is a link,
https://connect.mayoclinic.org/discussion/ca-15-3-cancer-tumor-marker/
Being MBC is a hard label to come to terms with, I hope you don’t focus too much on the numbers. They can really make me crazy when I do that.
How are you doing now? Have you visited any of the other discussions yet?