Between 70 and 90 percent of women with newly diagnosed, early-stage breast cancer are candidates for breast-conserving surgery, or lumpectomy, followed by radiation. In this procedure, surgeons remove the cancer along with a small amount of normal tissue surrounding the tumor — known as a surgical margin — to reduce the chance of leaving cancer cells behind.
Roughly 25 percent of women who receive a lumpectomy return to the operating room to have additional normal tissue removed. Of these women, approximately half have negative margins — defined as no tumor cells at the edge of the lumpectomy specimen. It has been widely thought that increasing the surgical margin would lower the risk of the cancer returning in that breast.
Now a new guideline issued jointly by two medical organizations recommends against performing this second procedure following lumpectomy. The guideline is expected to save patients from unnecessary surgery while still minimizing the risk of the cancer returning.
“It was important for us to create this guideline because we want women to have the confidence to select a lumpectomy rather than a mastectomy when medically possible and breast cancer physicians to be confident about knowing when a margin is adequate,” says Monica Morrow, Chief of Breast Cancer Surgery at Memorial Sloan Kettering, who cochaired the new guideline development.
Dr. Morrow notes that some women with early-stage breast cancer choose to have a mastectomy (removal of the entire breast) rather than a lumpectomy due to fears of cancer recurrence.
Determining Risk of Recurrence
After conducting a review of the available scientific evidence, a panel of breast cancer experts from the Society of Surgical Oncology (SSO), the American Society for Radiation Oncology (ASTRO), the American Society of Clinical Oncology (ASCO) , the American Society of Breast Surgery (ASBS), and the College of American Pathologists (CAP), as well as patient advocates, found that removing additional tissue did not significantly decrease the risk of recurrence in the same breast in women who received radiation treatments to the entire breast, which is standard practice.
This was found to be true regardless of a woman’s age and whether she had one of the more aggressive, triple-negative cancer types.
Based on its findings, the multidisciplinary panel, which reviewed 33 studies involving 28,162 patients, developed comprehensive, evidence-based guidelines for lumpectomy margins in an effort to spare many women from unnecessary surgery.
“The definition of the appropriate surgical margin for breast cancer has been a major controversy for decades, but we see excellent outcomes in women who undergo lumpectomy followed by radiation therapy,” says Dr. Morrow.
In general, the ten-year survival rate is considered the same for both mastectomy and lumpectomy plus radiation therapy, but lumpectomy offers a faster recovery time and improved cosmetic outcomes while lowering total healthcare costs.
The new guideline is endorsed by the SSO, ASTRO, ASCO, and the ASBS. It can be downloaded on the SSO’s website, at www.surgonc.org/margins-study. Additional resources can be found in the SSO’s Annals of Surgical Oncology.