My cousin has been on Tamoxifen for years with no side effects. I read that the Uterine Cancer risk is very low, but you would have to ask your doctor about that. It is very good for your bone health though, while the Aromatase therapy you might take after menopause is not. So, there is that. I also was diagnosed with LCIS and my surgeon said it was nothing to worry about as it rarely goes outside the ducts. She did remove it though, which brings me to your first sentence. How do you have DCIS without breasts and if you have had a mastectomy, they would surely have removed it? I wonder if you can still have a mammogram, even after your surgery? Questions for your doctor! I hope all goes well for you going forward. Blessings!