DCIS, an acronym (abbreviation involving initials) for ductal carcinoma in situ (also called intraductal carcinoma), is the most common form of non-invasive, early-stage breast cancer. Approximately 20% of newly diagnosed cases of breast cancer are DCIS.
Typically, DCIS is suspected when microcalcifications (tiny deposits of calcium) are observed on mammograms.
DCIS occurs when cancer cells have filled the breast ducts, but have not spread to the surrounding fatty or connective tissue of the breast or to any other part of the body.
Fortunately, almost all cases of DCIS are curable. For example, almost all women who are diagnosed with DCIS and treated early survive at least 5 years post diagnosis.
Several different types of DCIS are possible, however. For example, ductal comedocarcinoma consists of DCIS and areas of necrotic (degenerating) cancer cells. Ductal comedocarcinoma is a more aggressive type of DCIS.
If not treated, nearly one-fourth of all DCIS cases can develop into invasive cancer within 5 to 10 years. Such invasive forms of cancer are much more difficult to cure.