Breast Pathology and Cancer Diagnosis

Ductal carcinoma In Situ

DCIS is an early form of breast cancer and accounts for about 12% of all breast cancers. When cancer cells have developed within the ducts of the breast but remain within the ducts (‘in situ’), it is called DCIS. The cancer cells have not yet developed the ability to spread outside these ducts into the surrounding breast tissue or to other parts of the body. As a result of being confined to the ducts, DCIS has a very good prognosis. If DCIS is left untreated, the cancer cells may develop the ability to spread outside the ducts, into the surrounding breast tissue. This is known as invasive breast cancer. Invasive cancer has the potential to also spread to other parts of the body. In some cases, DCIS will never develop further or grows so slowly that it would never cause harm during that person’s lifetime. Although the size and grade of the DCIS can help predict if it will become invasive, there is currently no way of knowing if this will happen. High-grade DCIS is more likely to become an invasive breast cancer than low-grade DCIS and do so more quickly. Although DCIS is an early form of breast cancer with a very good prognosis, people understandably may feel very anxious and frightened by the diagnosis. People can often struggle to come to terms with being offered treatments such as a mastectomy, at the same time as being told their DCIS may never do them any harm.