DCIS stands for ductal carcinoma in situ, which is a non-invasive form of breast cancer. DCIS is a condition in which abnormal cells are found in the lining of the milk ducts of the breast. These abnormal cells have not invaded the surrounding breast tissue, and are considered to be pre-cancerous or "stage 0" breast cancer.

​​​​​​​While DCIS is not considered to be life-threatening on its own, if left untreated, it can develop into invasive breast cancer, which can be more difficult to treat. Treatment options for DCIS may include surgery to remove the abnormal cells, radiation therapy, and/or hormone therapy. The best course of treatment will depend on the individual case, and should be discussed with a healthcare provider.