Did you have an Oncotyoe test. Did it show your risk of distant Metastasis in 5-9 years. Surgery is always 98perrcent. That other 2 percent the way I see it is easily that one or 2 little cells that get away and can lodge somewhere else in your body and show up years later . You could have taken Inhibitors and been so allergic you may have stopped as has been the experience of some . So you cannot say conclusively that you got bone cancer because you did not take the inhibitors. Cancer cells are very tricky and are geniuses. I always imagine them as little parasites always trying to judge my body's next move and find a way around.I had mastectomy for invasive cancer ,clear margins, no lymph nodes involved. My oncotype was high and my oncologist has me on chemo to zap any cells that may have gotten away and also to disrupt the cancer DNA . Is it a guarantee? We won't know till years from now. After researching I wanted to be armed with an option in case AI don't work out for me and the chemo has not been bad at all .