DCIS is the most common type of noninvasive breast cancer, with about 60,000 new cases in the United States each year. About 1 in every 5 new breast cancer cases is ductal carcinoma in situ.
Women with DCIS are at higher risk for having cancer return following treatment, although the chance of a recurrence is under 30%. Most recurrences occur within 5 to 10 years after the initial diagnosis, and may be invasive or noninvasive. DCIS also carries a heightened risk for developing a new breast cancer in the other breast. A recurrence of DCIS is not life threatening, but will require additional treatment.
The type of therapy selected may affect the likelihood of recurrence. Treating ductal carcinoma in situ with a lumpectomy (breast-conserving surgery) without radiation therapy carries a 25–35% chance of recurrence. Adding radiation therapy to the treatment decreases this risk to approximately 15%. Currently, the long-term survival rate for women with DCIS is nearly 100%.
DCIS is divided into several subtypes, mainly according to the appearance of the tumor. These subtypes include micropapillary, papillary, solid, cribriform and comedo.