Definition

A condition in which cells that look mostly like normal cells under a microscope are found in the lining of a breast duct. The abnormal cells have not spread outside the duct to other tissues in the breast. Low-grade ductal carcinoma in situ tends to grow more slowly than intermediate-grade or high-grade ductal carcinoma in situ. It is also less likely to come back or become invasive breast cancer and spread to other tissues. Also called grade I DCIS, grade I ductal carcinoma in situ, and low-grade DCIS.