intraductal carcinoma (IN-truh-DUK-tul KAR-sih-NOH-muh)
A noninvasive condition in which abnormal cells are found in the lining of a breast duct. The abnormal cells have not spread outside the duct to other tissues in the breast. In some cases, intraductal carcinoma may become invasive cancer and spread to other tissues. At this time, there is no way to know which lesions could become invasive. Also called DCIS and ductal carcinoma in situ.