I don't have much follow up at 5 years and later, after doing 5 years of letrozole. My oncologist refers me back to PCP for x-rays if I have a concern about bone pain. If you are concerned about the other breast, first step would be to request a mammogram and breast exam by your PCP. I think oncologists are pretty inundated right now and after 5 years it seems we aren't really active patients. There is no way to know if cancer has recurred or spread other than imaging, to my knowldege,. Some docs do blood markers but most do those after stage 4 diagnosis I believe.