A study has found that removing more tissue during lumpectomy or partial mastectomy cuts the number of women who need more surgery later in half.
The study was presented on May 30, 2015 at the American Society of Clinical Oncology (ASCO) Annual Meeting and published online on the same day by the New England Journal of Medicine:
- Read the ASCO Annual Meeting abstract of “Can routine cavity shave margins (CSM) improve local control in breast cancer? Initial results of the SHAVE trial, a prospective randomized controlled trial of routine CSM vs. standard partial mastectomy (SPM).”
- Read the article in the New England Journal of Medicine: “A Randomized, Controlled Trial of Cavity Shave Margins in Breast Cancer.”
Lumpectomy or partial mastectomy (also called breast-conserving surgery) followed by radiation therapy is generally considered to be as good as mastectomy for women diagnosed with early-stage breast cancer with an average risk of the cancer coming back (recurrence). Earlier research has shown that recurrence risk was about the same with either treatment.
Note: Lumpectomy is technically a form of partial mastectomy, but more tissue usually is removed in partial mastectomy than lumpectomy. For easier understanding, we’re going to call both surgeries “lumpectomy” for the rest of this article.
During lumpectomy, the surgeon removes the cancer tumor and some of the normal tissue (called the margin) that is around it. After lumpectomy, a pathologist carefully examines the tissue that was removed to see if cancer cells are in the margins. Margins that have no cancer are called “negative” or “clean.” Margins that have cancer cells are called “positive.”
In a perfect world, your surgeon would learn the status of the margins before the lumpectomy is completed, so as much tissue as needed can be removed until the margins are clean. Unfortunately, analyzing the removed tissue takes about a week. Sometimes after the pathology report is done, the margins are found to contain cancer cells and more surgery is needed. This additional surgery is called a re-excision lumpectomy. Doctors estimate that 20% to 40% of women who have lumpectomy to remove early-stage breast cancer need to have more surgery later because of positive margins.
Because all the breast tissue is removed during a mastectomy, there’s usually no need for more surgery.
This study, done by researchers at Yale University, involved 235 women ages 33 to 94 who had been diagnosed with stage 0, stage I, stage II, or stage III breast cancer who were scheduled to have lumpectomy.
All the women had a standard lumpectomy, and the four surgeons who did all the operations removed as much tissue as they thought necessary to ensure clean margins. In the operating room, the women were then randomly assigned to one of two groups:
- one group (125 women) had no more tissue removed
- the second group (126 women) had more tissue removed by a procedure called cavity shave margins
In cavity shave margins, the surgeon removes an extra layer of tissue from around the inside of the hole that is left when the cancer tumor is removed.
The researchers then looked to see how many women had positive margins after lumpectomy surgery. The researchers also asked the women to rate the cosmetic results of their surgery.
The results showed that just after all the women had standard lumpectomy, about the same number of women in each group had positive margins:
- 34% of women who were going to have no more tissue removed had positive margins
- 36% of the women who were going to have cavity shave margins had positive margins
But after the women in the second group had the cavity margin procedure done, the percentage of women with positive margins in that group dropped to 19%.
Fewer women who had the cavity shave margins procedure needed more surgery -- 10% -- compared to 21% of the women who didn’t have the procedure. This difference was statistically significant, which means that it was likely due to the women having extra tissue removed rather than just because of chance.
The women in each group were similarly pleased with the results: More than 85% of the women in both groups rated the cosmetic results as good or excellent.
"Despite their best efforts, surgeons could not predict where the cancer was close to the edge," said the study's lead author, Anees Chagpar, M.D., M.P.H., associate professor of oncology surgery at the Yale School of Medicine and director of The Breast Center at Smilow Cancer Hospital at Yale-New Haven. "Taking cavity shave margins cut the positive margin rate in half, without compromising cosmetic outcome or increasing complication rates."
The researchers plan to follow the women in the study for 5 years to see if the cavity shave margin technique lowers recurrence rates.
If you’ve been diagnosed with early-stage invasive breast cancer or DCIS and are planning your treatment, you and your doctor will consider which type of surgery makes the most sense for you based on your unique situation. For many women, lumpectomy followed by radiation therapy is a good option and more attractive than mastectomy, both physically and emotionally.
Still, choosing lumpectomy may mean possible repeat surgery after the lumpectomy tissue removed is analyzed. Talk to your doctor about any concerns you have about this possibility and how your concerns might influence the type of surgery you choose. You might want to bring up this study and ask if your surgeon is familiar with the cavity shave margin technique. Together, you and your doctor can decide on a surgical plan that is right for YOU.
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