Most women should have their first mammogram when they are 40. If your mother had breast cancer at a young age, or if several female relatives have had breast cancer young, many physicians recommend starting 10 years younger than the youngest relative. Thus, if your mother was 45 when she had breast cancer, you should have your first mammogram when you are 35.
Tamoxifen is a drug that is very similar to estrogen.
It binds to the sites on breast tissue cells where estrogen would bind, and therefore blocks estrogen. Because estrogen cannot bind, it cannot stimulate the breast. It has effects on other parts of the body as well. Fibrocystic changes are very common, in fact, most American women have it. Most women are not at an increased risk of breast cancer.