This summary table contains detailed information about research studies. Summary tables offer an informative look at the science behind many breast cancer guidelines and recommendations. However, they should be viewed with some caution. In order to read and interpret research tables successfully, it is important to understand some key concepts. Learn how to read a research table.
Introduction: Ductal carcinoma in situ (DCIS) is a non-invasive breast cancer. “In situ” means "in place." In DCIS, the abnormal cells are contained in the milk ducts, but have not invaded nearby breast tissue.
Without treatment, DCIS can progress to invasive breast cancer over time. So, all cases of DCIS are treated. Treatment involves surgery, with or without radiation therapy. Some women may also take tamoxifen (learn more).
Radiation therapy is not given to women who are treated with mastectomy for DCIS.
Lumpectomy for DCIS is usually followed by radiation therapy to lower the risk of invasive breast cancer and DCIS recurrence.
A meta-analysis that combined the results of four randomized clinical trials showed lumpectomy plus radiation lowered the risk of invasive breast cancer after DCIS (in the same breast as the DCIS) by 50 percent compared to lumpectomy alone .
Overall survival appears similar for women with DCIS who have lumpectomy with or without radiation therapy [1-2].
Learn more about treatment for DCIS.
Learn about the strengths and weaknesses of different types of studies.
Study selection criteria: Randomized clinical trials with at least 500 participants and five or more years of follow-up and meta-analyses.
Study Population (number of participants)
Percent of Women who Developed Invasive Breast Cancer*
Overall Survival (for length of follow-up)
Radiation Therapyafter Lumpectomy
NoRadiation Therapyafter Lumpectomy
No RadiationTherapyafter Lumpectomy
Randomized clinical trials
UK, Australia, New Zealand (UK/ANZ) DCIS Trial 
Swedish Breast Cancer Group 
European Organization for Research and Treatment of Cancer (EORTC) 
National Surgical Adjuvant Breast and Bowel Project (NSABP) B-17 
Radiation Therapy Oncology Group 
Less than 1%
Cochrane Collaboration 
* Invasive breast cancer in the same breast treated for DCIS
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