@myoga Good questions, and unfortunately I don't have the medical expertise to know the exact answers. But I will do some research and see if I can find something worth sharing. I think what you say here is correct--"Is it because the test can not detect any estrogen levels below 10." The five years is standard, although some women go for ten years. When I hit five years my oncologist said we'd decide on whether or not to continue--based in part upon bone density. But that is probably a question for your doctor. I hope to add more here. and that others can weigh in as well.