Ductal carcinoma in situ is diagnosed when malignant-appearing cells are found within the ducts that connect the milk-producing lobules to your nipples.

Ductal carcinoma in situ is much more common than lobular carcinoma in situ, and is a very early cancer diagnosis. If found it can be removed from the breast before it develops into invasive cancer and affects the surrounding breast tissue.

This type of cancer is usually treated locally with lumpectomy and radiation therapy. Rarely is a mastectomy recommended for this type of tumor.

Most breast cancers start in the ducts. This figure shows "intraductal carcinoma in situ," which means that cancer cells have not invaded surrounding tissues.