Three leading national cancer organizations, -- the Society of Surgical Oncology (SSO), the American Society for Radiation Oncology (ASTRO) and the American Society of Clinical Oncology (ASCO) -- issued a consensus guideline for physicians treating women who have ductal carcinoma in situ (DCIS) treated with breast-conserving surgery with whole breast irradiation.
The new guideline has the potential to save many women from unnecessary surgeries while reducing costs to the health care system. The three leading national cancer organizations together published the new guideline in their respective journals, the Annals of Surgical Oncology, Practical Radiation Oncology and the Journal of Clinical Oncology.
The groups concluded, "The use of a two millimeter margin as the standard for an adequate margin in DCIS treated with whole breast radiation therapy (WBRT) is associated with low rates of recurrence of cancer in the breast and has the potential to decrease re-excision rates, improve cosmetic outcome, and decrease health care costs. Clinical judgment should be used in determining the need for further surgery in patients with negative margins less than two millimeters. Margins more widely clear than two millimeters do not further reduce the rates of recurrence of cancer in the breast and their routine use is not supported by evidence."
To determine the margin width, a pathologist paints the outer surface of the tissue that's been removed with ink. A clear, negative, or clean margin means there are no cancer cells at the outer inked edge of tissue that was removed, while a positive margin means that cancer cells extend to the inked tissue. A 2010 survey found that 42 percent of surgeons recommended a two millimeter margin, while 48 percent favored larger margins.
To date, approximately one in three women who are treated surgically for DCIS undergo a re-excision, due in part to the lack of consensus on what constitutes an adequate negative margin. Re-excisions have the potential for added discomfort, surgical complications, compromise in cosmetic outcome, additional stress for patients and families, and increased health care costs. They have also been associated with patients choosing to have double mastectomies.
"An important finding from the review of the published literature performed to provide evidence for this guideline is that margin widths greater than two millimeters (approximately 1/8th of an inch) do not reduce the risk of cancer recurring in the breast in women with DCIS who are treated with lumpectomy and whole breast radiation therapy," said Monica Morrow, MD, past SSO President and panel co-chair, Memorial Sloan Kettering Cancer Center, Breast Service, Department of Surgery.
The panel established by SSO, ASTRO and ASCO to develop the consensus guideline relied on a review examining the relationship between margin width and cancer recurrence in the breast that included 30 studies involving 7,883 patients, as well as other studies relevant to this topic.
"With this guideline, it is our two-pronged goal to help physicians improve the quality of care they provide to women undergoing surgery for DCIS and ultimately improve outcomes for those patients. We hope the guideline also translates into peace of mind for women who will know that future surgeries may not be needed," said Mariana Chavez-MacGregor, MD, University of Texas MD Anderson Cancer Center and panel member representing ASCO.
Dr. Morrow advised that if a woman with a negative margin is told to have a re-excision, she needs to ask what factors are prompting the surgeon to recommend that re-excision. Bruce G. Haffty, MD, immediate past chair of ASTRO's Board of Directors, said this new guideline builds on previously published standards and will benefit clinicians who have struggled with margin width in women with DCIS.
"This important cooperative guideline generated by these societies involved a multidisciplinary panel of surgical, medical and radiation oncologists, as well as pathologists and statistical experts. While the guideline appropriately allows for some flexibility and clinical judgment in interpretation, the conclusion that a two millimeter margin width is adequate in patients with DCIS will be helpful and reassuring to clinicians and patients in clinical decision-making."
"This guideline is another important step in our collective work to ensure that women are receiving the best and most appropriate breast cancer care," said Susan G. Komen President and CEO Judy Salerno, MD, MS. "We were pleased to support the panel, both through funding and by lending the patient perspective to these discussions, and hope it empowers both patients and physicians to make well-informed treatment decisions that will reduce the likelihood for re-excisions."
This study was conducted by the panel co-chaired by Dr. Morrow and ASTRO representative Meena S. Moran, MD, Department of Therapeutic Radiology, Yale School of Medicine, Yale University. This guideline has also been endorsed by the American Society of Breast Surgeons.