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Ductal Carcinoma In Situ (DCIS)
Hospital  >  Care Programs  >  Odette Cancer Program  >  Breast cancer care  >  Breast cancer patient education  >  Ductal Carcinoma In Situ (DCIS)  >  What is Ductal Carcinoma In Situ (DCIS)
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What is Ductal Carcinoma In Situ (DCIS)

DCIS is abnormal cells within the ductal structures (milk ducts) of the breast. It is known as Stage 0, or “pre-cancer” which means that the abnormal cells have not spread into any other tissue beyond the milk ducts. DCIS can be in one or many areas of the breast and may be small or large. DCIS is common.

It is important to treat DCIS because it may develop into invasive breast cancer. All women are offered treatment for DCIS as we cannot yet predict which DCIS will turn into an invasive breast cancer.

If DCIS is left untreated, some women will develop invasive breast cancer. 

An image that illustrates what invasive breast cancer looks like in a milk duct, versus what a normal milk duct looks like.