I had the same cancer, stage 1, lumpectomy. I am going to have 2 weeks of radiation, and the 5 years on Tamoxifen. I am going to be in a trial with the Tamoxifen. 20mg Tamoxifen every day or 10 mg Tamoxifen every other day. I am hoping I get chosen to do the every other day. I feel good about my decision for me. Everyone has to make that decision, but I trust my doctors entirely. Best of luck to you with whatever decision you make.