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Treatment Guidelines

There are several resources available that provide information on the latest cancer treatment guidelines. The information below serves as an index for various information databases, as well as specific guidelines organized by disease site.

The Society of Surgical Oncology (SSO) leadership evaluates external organization’s endorsement opportunities to determine whether the document addresses a gap in surgical oncology, fosters quality care in surgical oncology and is a topic of interest to the SSO membership. An organization’s request must meet several criteria and the review process make take up to three months. For additional information and to complete an Endorsement Request Form please click here.

Management of Hereditary Breast Cancer: ASCO, ASTRO and SSO Guideline


Date: April 3, 2020

SSO collaborated with the American Society of Clinical Oncology and the American Society for Radiation Oncology to develop, Management of Hereditary Breast Cancer: ASCO, ASTRO and SSO Guideline. The multidisciplinary, expert panel addressed 10 clinical practice questions in the guideline. Recommendations were developed using the ASCO modified Delphi formal consensus methodology. In addition to SSO participation in the Expert Panel, the Guideline was reviewed by members of SSO’s Breast Disease Site Work Group, the Chair of the SSO Quality Committee and approved by the SSO Executive Council.

In addition, SSO’s Breast Disease Site Work Group Chair and Vice Chair published the following Editorial on the Guideline. McGuire KP, Mamounas EP. Management of hereditary breast cancer: ASCO, ASTRO, and SSO Guideline. Ann Surg Oncol. 2020. https:doi.org/10.1245/s10434-020-08396-8. The editorial comments on various aspects of the Guideline including surgical management, radiation therapy and systemic therapy.

Additional Resources:

Guideline Summary Table

Guideline Slides

SSO, ASTRO and ASCO Issue Joint Statement on Margins for Breast-Conserving Surgery with Whole Breast Irradiation in Ductal Carcinoma In Situ

ROSEMONT, Ill., ARLINGTON, Va., ALEXANDRIA, Va. – Three leading national cancer organizations today 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 Society of Surgical Oncology (SSO), the American Society for Radiation Oncology (ASTRO) and the American Society of Clinical Oncology (ASCO) 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.”

Supported by a grant from Susan G. Komen, SSO spearheaded the guideline initiative and established a panel of experts from the three organizations, including clinicians, researchers and a patient advocate to create the new guideline to provide clarity regarding the optimal negative margin width for ductal carcinoma in situ.

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.

View the complete Consensus Guideline on Margins for Breast-Conserving Surgery with Whole Breast Irradiation in Ductal Carcinoma In Situ.

*Affirmed September 2019: Since this guideline was published more than 3-5 years ago, the guideline development panel evaluated the content for currency, accuracy and validity. Based on their recommendation, the SSO, ASTRO, and ASCO have affirmed that an update to the guideline is not required.

SSO-ASTRO Consensus Guideline Margins for Breast-Conserving Surgery with Whole Breast Irradiation in Stage I and II Invasive Breast Cancer

Since breast-conserving therapy was introduced more than 40 years ago, significant changes in breast-imaging technology, pathology assessment and the use of systemic therapy have improved patient outcomes. These changes have resulted in a decreased rate of ipsilateral breast tumor recurrence (IBTR, also called local recurrence or in breast recurrence). This prompted the Society of Surgical Oncology (SSO), in collaboration with the American Society of Radiation Oncology (ASTRO), to undertake an evidence based consensus to provide a clear and comprehensive approach for practitioners.

With funding from the Susan G. Komen, a multidisciplinary panel of experts assembled in July 2013 to examine the evidence on the relationship between the amount of tissue removed surrounding a breast cancer, called a surgical margin, and ITBR. The key recommendations from this comprehensive review are summarized below. The complete guideline document, as well as the supporting evidence from the meta-analysis can be found in the “Annals of Surgical Oncology,” here

SSO believes that the information in this guideline, which has been endorsed by the American Society of Clinical Oncology (ASCO) and the American Society of Breast Surgeons (ASBS), can be used to decrease unnecessary margin re-excisions while maintaining excellent outcomes in breast conserving surgery and will serve as a definitive resource to the profession.


Controversy exists regarding the optimal margin width in breast-conserving surgery for invasive breast cancer.


A multidisciplinary consensus panel considered a meta-analysis of margin width and ipsilateral breast tumor recurrence (IBTR) from a systematic review of 33 studies including 28,162 patients as the primary evidence base for consensus. The results of randomized clinical trials, reproducibility of margin assessment, and current patterns of multimodality care were also considered.


Positive margins (ink on invasive carcinoma or ductal carcinoma in situ) are associated with a two-fold increase in the risk of IBTR compared to negative margins. This increased risk is not mitigated by favorable biology, endocrine therapy or a radiation boost. More widely clear margins than no ink on tumor do not significantly decrease the rate of IBTR. There is no evidence that more widely clear margins reduce IBTR for young patients, unfavorable biology, lobular cancers, or cancers with an extensive intraductal component.


The use of no ink on tumor as the standard for an adequate margin in invasive cancer in the era of multidisciplinary therapy is associated with low rates of IBTR and has the potential to decrease re-excision rates, improve cosmetic outcomes, and decrease healthcare costs.

The 2013 SSO/ASTRO Guideline on Margins in Breast-Conserving Surgery for Invasive Cancer is summarized here.

Positive Margins

A positive margin, defined as ink on invasive cancer or ductal carcinoma in situ (DCIS), is associated with at least a two-fold increase in IBTR. This increased risk in IBTR is not nullified by:

a) Delivery of a boost dose of radiation

b) Delivery of systemic therapy (endocrine, chemotherapy, or biologic), or

c) Favorable biology

Negative Margin Widths

Negative margins (no ink on tumor) minimize the risk of IBTR. Wider margin widths do not significantly lower this risk. The routine practice to obtain wider negative margin widths than no ink on tumor is not indicated.

Systemic Therapy

The rates of IBTR are reduced with the use of systemic therapy. In the uncommon circumstance of a patient not receiving adjuvant systemic therapy, there is no evidence suggesting that margins wider than no ink on tumor are needed.

Biologic Subtypes

Margins wider than no ink on tumor are not indicated based on biologic subtype.

Radiation Therapy Delivery

The choice of whole breast radiation delivery technique, fractionation, and boost dose should not be dependent on the margin width.

Invasive lobular carcinoma and lobular carcinoma in situ (LCIS)

Wider negative margins than no ink on tumor are not indicated for invasive lobular carcinoma. Classic LCIS at the margin is not an indication for re-excision. The significance of pleomorphic LCIS at the margin is uncertain.

Young age

Young age (≤40 years) is associated with both increased IBTR after BCT as well as increased local relapse on the chest wall after mastectomy, and is also more frequently associated with adverse biologic and pathologic features. There is no evidence that increased margin width nullifies the increased risk of IBTR in young patients.

Extensive Intraductal Component (EIC)

An EIC identifies cases that may have a large residual DCIS burden after lumpectomy. There is no evidence of an association between increased risk of IBTR and EIC when margins are negative.

Consensus Panel Co-Chairs

Monica M. Morrow, MD, Breast Service, Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY

Meena S. Moran, MD, Department of Therapeutic Radiology, Yale School of Medicine, Yale University, New Haven, CT

Panel Participants

S. Schnitt, MD, Department of Pathology, Harvard Medical School, Boston, MA

A. Giuliano, MD, Department of Surgery, Cedars Sinai Medical Center, Los Angeles, CA

J. Harris, MD, Department of Radiation Oncology, Harvard Medical School, Boston, MA

S. Khan, MD, Department of Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL

J. Horton, MD, Department of Radiation Oncology, Duke University Medical Center, Durham, NC

S. Klimberg, MD, Department of Surgery, University of Arkansas for Medical Sciences, Fayetteville, AR

M. Chavez-MacGregor, MD, Department of Medical Oncology, University of Texas MD Anderson Cancer Center, Houston, TX

G. Freedman, MD, Department of Radiation Oncology, University of Pennsylvania School of Medicine, Philadelphia, PA

N. Houssami, MD, PhD, School of Public Health, Sydney Medical School, University of Sydney, Sydney NSW 2006, Australia

PL Johnson, Advocate in Science, Susan G. Komen

Download page as PDF

Consensus Guidelines News Release

February 2014 Guideline Margins

National Cancer Institute

American Society of Breast Cancer Surgeons

American Society of Clinical Oncology

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