infiltrating ductal carcinoma (IN-fil-TRAY-ting DUK-tul KAR-sih-NOH-muh)
The most common type of infiltrating breast cancer. It begins in the lining of the milk ducts (thin tubes that carry milk from the lobules of the breast to the nipple) and spreads outside the ducts to surrounding normal tissue. Infiltrating ductal carcinoma can also spread through the blood and lymph systems to other parts of the body. Also called invasive ductal carcinoma.