What it is ductal carcinoma in situ (DCIS)

Doctors also call this type of carcinoma in situ intraductal carcinoma. It is one of the most common types of breast cancer, according to the American Cancer  Society. Ductal means that cells are growing in the milk ducts of the breasts. There is an estimated 20 percent of breast cancers diagnosed annually in the United States are DCIS, equivalent to about 60,000 cases.