I had lumpectomy in June 2023 and also Oncotype positive. Went through chemo and radiation and now on AI therapy. I have also questioned the same - should I have done the mastectomy which would have avoided the radiation (and have since learned insurance may pay for bilateral mastectomy). But in my research, while mastectomy does decrease reoccurrence in the breast tissue (none there) in the long run, it does not change the outcome ratios. Plus there are side effects to the mastectomy as well, even without reconstruction. So I am now more comfortable with my decision but would definitely re-examine my options if I have a reoccurrence.