DCIS is a condition of abnormal, but not cancerous, cells found in the lining of the milk ducts, and has not spread into nearby tissue. It is the most common type of non-invasive breast ‘cancer.’ Non-invasive means that the abnormal cells do not move from where they are found and therefore, DCIS is often referred to as a ‘precancer.’

DCIS was rarely diagnosed before 1980, but with increased rates of screening mammography, DCIS detection has come to represent 20-25% of all breast cancer diagnoses.

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