Breast-conserving surgery (BCS) for ductal carcinoma in situ (DCIS) should aim for wide margins to keep recurrence risk low, even if the patient is receiving radiotherapy, according to a new meta-analysis study.

Researchers at the University of Minnesota School of Public Health (Minneapolis, USA) searched the PubMed database for studies of DCIS published in English between January 1970 and July 2010 to examine the relationship between ipsilateral breast tumor recurrence (IBTR) and margin status after BCS for DCIS. Women with DCIS were stratified into two groups - BCS with or without radiotherapy. The researchers then estimates the odds ratios (OR) of IBTR for groups with negative margins and positive margins, as well as examining specific margin thresholds using mixed treatment comparisons and metaregression techniques.

The results showed that in 21 studies, a total of 1,066 IBTR events occurred in 7,564 patients, including BCS alone (565 IBTR events in 3,098 patients) and BCS with radiotherapy (501 IBTR events in 4,466 patients). Negative margins were associated with reduced risk of IBTR in both patients with radiotherapy and in patients without radiotherapy. The researchers concluded that a negative margin of at least 10 mm cut ipsilateral recurrence risk by a significant 54%, compared with getting a negative margin of only greater than 2 mm. The study was published early online on March 22, 2012, in the Journal of the National Cancer Institute.

“Within cosmetic constraint, surgeons should attempt to achieve negative margins as wide as possible in their first attempt,” concluded lead author Shi-Yi Wang, MD, and colleagues. “A negative margin threshold greater than 10 mm is the best option compared with other margin thresholds. Radiotherapy should complement the targeting of wider free margins to minimize ipsilateral breast tumor recurrence.”

DCIS is the most common type of noninvasive breast cancer, in which the abnormal cells are contained inside the milk ducts. If DCIS is not treated, it may eventually develop into invasive breast cancer, which can spread outside the ducts into the breast tissue and then possibly to other parts of the body. Since DCIS cannot usually be felt as a breast lump or other breast change, most cases are diagnosed following routine screening with mammograms or ultrasound, appearing as microcalcifications.

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