ductal carcinoma in situ (DUK-tul KAR-sih-NOH-muh in SY-too)
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, ductal carcinoma in situ 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 intraductal carcinoma.