Consensus guideline: Wider DCIS margins don’t cut breast-cancer recurrence

An expert review panel incorporating input from three of the top national cancer organizations is recommending a 2-millimeter rim of healthy tissue for women with ductal carcinoma in situ (DCIS) treated with breast-conserving surgery and whole-breast radiation therapy.

The panel published its guideline Aug. 15 in their societies’ respective journals.

“Use of a 2-mm margin as the standard for an adequate margin in DCIS treated with whole-breast irradiation is associated with lower rates of ipsilateral breast tumor recurrence and has the potential to decrease re-excision rates, improve cosmetic outcomes and decrease healthcare costs,” the authors conclude, noting that about one-third of DCIS surgeries are currently repeated.

The panel arrived at a consensus recommendation after analyzing 20 published studies comprising 7,883 patient cases.

Perhaps unsurprisingly, despite the multi-player consensus, the publication has reignited a long-simmering debate over optimal negative margin width for these patients. (More on that below.)

A 2-mm margin minimizes the risk of ipsilateral breast tumor recurrence compared with smaller negative margins, the authors stress, and wider margins don’t significantly decrease such recurrence compared with 2-mm margins.

Publishing the study findings simultaneously this week were the Society of Surgical Oncology (Annals of Surgical Oncology), American Society for Radiation Oncology (Practical Radiation Oncology) and the American Society of Clinical Oncology (Journal of Clinical Oncology).

To contextualize their analysis and conclusions, the authors note:

“Retrospective single-institution studies have suggested that a negative margin width of 1 cm or more may eliminate the reduction in ipsilateral breast tumor recurrence seen with whole-breast radiation therapy, leading some to conclude that larger margins are also beneficial in patients undergoing whole-breast radiation therapy. Despite the widespread use of breast-conserving therapy for DCIS, there is still no consensus on what constitutes an optimal negative margin width. As a consequence, approximately one in three women attempting breast-conserving therapy for DCIS undergo re-excision. Re-excisions have the potential for added discomfort, surgical complications, compromise in cosmetic outcome, additional stress for patients and families, and increased healthcare costs and have been associated with conversion to bilateral mastectomy.”

The work has been endorsed by the American Society of Breast Surgeons, and Judith Salerno, MD, MS, president and CEO of the Susan G. Komen organization, hailed the guideline as “another important step in our collective work to ensure that women are receiving the best and most appropriate breast cancer care.”  

Not everyone is convinced.

In a combox comment attached to a news release on SSO’s website, surgeon Pat Whitworth, MD, of the Nashville Breast Center in Tennessee calls the guideline a “big step backwards.”

Whitworth says the guideline “undoes much of the good done with the invasive breast cancer guidelines, recapitulating the nonsensical history of treating DCIS more aggressively than invasive cancer and ‘angels on the head of a pin’ margin talk. Every study shows the majority are over-treated. Effort should be to see the minority of bad actors, not cookbook the entire population.”

The study panel was co-chaired by Monica Morrow, MD, of Memorial Sloan Kettering Cancer Center and Meena Moran, MD, of Yale.

Click here to read the news release and here for the full study report.