Experts Discuss New Guideline for Margins in Breast-Conserving Surgery

Breast Cancer News
September 5, 2014
By: 
Anna Shaffer, Contributing Writer

A panel of experts reviewed key points and limitations of a new national guideline on margins for lumpectomy, also called breast-conserving surgery, at the American Society of Clinical Oncology 2014 Breast Cancer Symposium in San Francisco yesterday. They also discussed how it can be used in clinical practice.

Lumpectomy removes the tumor from your breast, along with a rim of healthy tissue, called the margin. How large the margin needs to be has long been debated.

The goal of breast cancer surgery is to remove all the cancer from your breast. But because it can be hard to tell how much cancer is there, it may take two or three surgeries to remove it all.

Guideline Background

The guideline, issued by the American Society for Radiation Oncology and the Society of Surgical Oncology in February 2014, is based on an analysis of 33 research studies published from 1965 to 2013.

The studies included 28,162 people with stage I or II invasive breast cancer who were treated with standard radiation therapy to the whole breast. People treated with  neoadjuvant chemotherapy were not included in the research for the guideline.

The analysis showed that:

  • Positive margins, when the pathologist finds cancer cells in the healthy tissue, are associated with a two-fold increase in the risk of recurrence in the same breast compared with negative margins, healthy tissue that has no breast cancer cells.
    • This increased risk is not lowered by having less aggressive breast cancer subtypes, using hormonal therapy or getting an extra boost of radiation to the part of the breast that had the original tumor.
  • Removing larger margins that test negative does not significantly lower the rate of recurrence in the same breast.
  • There is no evidence that having larger, negative margins lowers the risk of recurrence in the same breast for young people or for those with more aggressive subtypes, cancer that begins in the  breast lobules, or contains  ductal carcinoma in situ (DCIS).

Guideline Summary

In addition to defining a standard margin size, the guideline also outlines surgical treatment that helps prevent multiple surgeries while maintaining the good outcomes seen with lumpectomy plus radiation therapy.

The guideline includes eight clinical practice recommendations focused on lowering recurrence rates in stages I and II invasive breast cancer.

Key Points Discussed During This Session

  • According to Monica Morrow, MD, breast cancer surgeon and chief of breast surgery at Memorial Sloan Kettering Cancer Center in New York, more than 26,000 re-excisions, additional surgery to remove remaining cancer in the breast, are performed every year.
  • Stuart J. Schnitt, MD, of Beth Israel Deaconess Medical Center and Harvard Medical School, said that less than 1 percent of tissue samples are truly evaluated with a microscope. When the margin is described as negative in the test report, it doesn’t mean there is no remaining tumor. And when the margin is described as positive, it does not mean there is tumor remaining in the breast.
  • Carol Lee, MD, of Memorial Sloan Kettering Cancer Center, discussed how  MRI can be used to assess margins in some situations.
  • Benjamin O. Anderson, MD, of the University of Washington, said that several factors, including surgeon and radiologist teamwork and surgical technique, can help reduce positive margins.
  • Harold J. Burstein, MD, PhD, of Dana-Farber Cancer Institute, said that tailored systemic (whole-body) treatment lowers risk of  local and  regional recurrence.
  • Bruce George Haffty, MD, of Rutgers Robert Wood Johnson Medical School, Rutgers Cancer Institute of New Jersey, presented a radiation oncologist’s view of positive, negative or close margins and whether or not there is a difference. Dr. Haffty believes that although a radiation boost to the part of the breast that had the original tumor lowers the chance of local recurrence, it may be eliminated in those over 60.

What This Means for You

This guideline may help you avoid additional surgery to remove remaining cancer in your breast after lumpectomy. It may also help reduce the risk of cancer returning to your breast.

Keep in mind this is a guideline, rather than a rule, for doctors, and that some limitations to the guideline exist. During this session, doctors were encouraged to use their own clinical judgment and flexibly in decision making. It’s important to discuss concerns with your care team as soon as they come up.

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