Hey @mjay, There is a CA 15.3 that doctors use to check early indicators and possible mets. I put the article below. I wonder if asking your physician for this every so often might be a good way to progress?
https://www.breastcancer.org/symptoms/testing/types/blood_marker#:~:text=Some%20doctors%20use%20marker%20test,to%20start%20treatment%20for%20recurrence.
@cindylb Cindy's husband has done cancer marker tests and she may be able to comment on how they went about getting their physician to treat with blood tests.

Do you only get checkups every 6 months?