I thought I would join this forum to help me decide as to whether or not to get a second mastectomy and to alos share my breast cancer experience. I have the ATM gene. I got breast cancer on the left breast, had a lumpectomy, radiation and took anastrozole for five years The anastrozole caused serious pain in thumb and hip joints which subsided when I stopped taking the drug. I read that if you have the atm gene, had a lumpectomy and radiation, you have a high risk of return breast cancer in the opposite breast within 5 years (contralateral breast cancer) That happened to me. I had a mastectomy on the new cancer (right breast). No radiation or chemo because it was er positive. The latest medical view is that the radiation treatment only increased the chances of being disease free by 5%. Then I went on letrozole. I got sever dry mouth which turned into permanent salivary glands damage. So I switched to tamoxifen and am comfortable I read that with the ATM gene after breast cancer treatment your chances of being desease free for the first 4 years is 85%, but 45% for the first 11 years. I am leaning towars getting a second mastectomy. Hope this helps others