DCIS is often discovered as microcalcifications – tiny calcium deposits that appear as very small, white specks on mammograms. DCIS is fairly common now comprising ~25% of all breast cancers. If left untreated, 20 to 25 percent of the women will go on to get invasive cancer in about 10 years. Treatment usually involves removal of all the DCIS followed by radiation therapy in most women. Some women have such extensive DCIS that they need a mastectomy but they can get reconstruction at the same time. In some patients, the addition of Tamoxifen has been shown to reduce the chance of recurrence and is therefore added to their therapy.