Ductal carcinoma in situ (DCIS) is the most common type of non-invasive breast cancer. Ductal means that the cancer starts inside the milk ducts, carcinoma refers to any cancer that begins in the skin or other tissues (including breast tissue) that cover or line the internal organs, and in situ means "in its original place." DCIS is called "non-invasive" because it hasn’t spread beyond the milk duct into any normal surrounding breast tissue. DCIS isn’t life-threatening, but having DCIS can increase the risk of developing an invasive breast cancer later on.
When you have had DCIS, you are at higher risk for the cancer coming back or for developing a new breast cancer than a person who has never had breast cancer before. Most recurrences happen within the 5 to 10 years after initial diagnosis. The chances of a recurrence are under 30%.
Women who have breast-conserving surgery (lumpectomy) for DCIS without radiation therapy have about a 25% to 30% chance of having a recurrence at some point in the future. Including radiation therapy in the treatment plan after surgery drops the risk of recurrence to about 15%. Learn what additional steps you can take to lower your risk of a new breast cancer diagnosis or a recurrence in the Lower Your Risk section. If breast cancer does come back after earlier DCIS treatment, the recurrence is non-invasive (DCIS again) about half the time and invasive about half the time. (DCIS itself is NOT invasive.)
According to the American Cancer Society, about 60,000 cases of DCIS are diagnosed in the United States each year, accounting for about 1 out of every 5 new breast cancer cases.
There are two main reasons this number is so large and has been increasing over time:
- People are living much longer lives. As we grow older, our risk of breast cancer increases.
- More people are getting mammograms, and the quality of the mammograms has improved. With better screening, more cancers are being spotted early.
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