Before mammography became the widely used breast cancer screening tool it is today, ductal carcinoma in situ, or DCIS, was a rare diagnosis. DCIS is a diagnosis given to women who have abnormal cells confined to milk ducts branching through the breast. Some believe more women are receiving this diagnosis incidentally, because they are regularly undergoing screening mammography. A finding that used to account for less than 5% of all newly diagnosed breast cancers now represents 25%.
DCIS has become one of those woolly diagnoses. The name carcinoma certainly sounds like it is cancer and the diagnosis evokes fear in the growing number of women who hear it. Still, some doctors, cancer institutions and breast cancer advocates are at odds about what to do about DCIS. It is a contentious subject because the diagnosis is problematic: It relies on perfections of imaging technology, pathology reports and a diagnostician's opinions.
What's in a Name?
The breast is comprised of lobular tissue that makes milk and ducts that carry milk out to the nipple. DCIS takes hold inside of the milk ducts. The cells that line the ducts sometimes grow to fill the ducts (atypical ductal hyperplasia) or become abnormal DCIS cells. Some argue that DCIS should lose to word "carcinoma" because it behaves more like a precursor, marker or future risk factor for invasive breast cancer. By definition, DCIS is not a life-threatening disease in itself because, as the name says, it stays put (in situ is Latin for "in the original place"). This is why DCIS is also called stage 0 or non-invasive cancer.