Margin shaving reduces positive margins, need for additional surgery in breast cancer

Issue: June 25, 2015

CHICAGO — Cavity shave margins significantly reduced positive-margin and re-excision rates among women undergoing partial mastectomy for breast cancer, according to results of the SHAVE trial presented at the ASCO Annual Meeting.

Perspective from Michele A. Gadd, MD

Cavity shave margins could potentially lead to significant reductions in morbidity and reoperation, the researchers also found.

“Twenty to forty percent of women who undergo a partial mastectomy for breast cancer have positive margins at final pathology,” Anees B. Chagpar, MD, MPH, associate professor of surgery at Yale School of Medicine and director of The Breast Center at Smilow Cancer Hospital at Yale-New Haven, told HemOnc Today. “This often requires a return trip to the operating room. Some [clinicians] have advocated routine cavity shave margins — the practice of taking a little bit more all around the cavity — while others have questioned whether this approach makes sense.”

Researchers had not conducted a prospective trial comparing the use of cavity shave margins to standard partial mastectomy, Chagpar said in an interview.

Chagpar and colleagues evaluated data from 235 patients (median age, 61 years; range, 33-94) with stage 0 to stage III breast cancer who were enrolled in the randomized, controlled SHAVE trial, the results of which were also published in The New England Journal of Medicine.

All patients underwent standard partial mastectomy with or without resection of selective margins prior to randomization. Randomization (1:1) occurred intraoperatively, when researchers assigned patients to receive further cavity shave margins resected during the procedure (shave group) or no further resection (no-shave group).

Researchers defined positive margins as the tumor touching the edge of the removed specimen for invasive cancer and the tumor within 1 mm of the removed specimen for in situ cancer.

Rate of positive margins served as the primary endpoint. Secondary endpoints included cosmesis and volume of tissue resected.

At final pathology researchers observed invasive cancer in 23% of patients (n = 54), in situ cancer in 19% of patients (n = 45) and both in 53% of patients (n = 125). Eleven patients exhibited no further disease.

Patients with invasive disease had a medium tumor size of 1.1 cm (range, 0-6.5) and patients with in situ disease had a median tumor size of 1 cm (range, 0-9.3).

Prior to randomization, researchers observed comparable rates of positive margins among the shave and no-shave groups (36% vs. 34%). However, patients in the shave group exhibited significantly decreased rates of positive margins following randomization (19% vs. 34%; P = .01).

Further, significantly fewer patients in the shave group underwent second surgery for margin clearance than patients in the no-shave group (10% vs. 21%; P = .02).

Researchers excised a significantly larger volume of tissue in the shave group compared with the no-shave group (115.1 cm³ vs. 74.2 cm³; P < .001).

Cavity shave margins also led to the discovery of further cancer in some patients, Chagpar said.

“Normally, if patients had a negative margin initially, we would all just go home and be happy with the outcome,” Chagpar said. “However, because 119 patients were randomized to the shave group, surgeons performed the shave margins anyway. We found further cancer in 11.8% of the patients who were shaved, disease we would heretofore not have known was there.”

Researchers did not observe a significant difference in patients’ postoperative cosmetic perceptions. Three patients in the no-shave group developed postoperative hematomas.

“We were able to cut the positive margin rate and the reoperation rate in half with a very simple technique that takes about 10 minutes,” Chagpar said. “At both my institution and at institutions around the country, this is going to be practice changing.” – by Cameron Kelsall and Alexandra Todak

Reference:

Chagpar AB, et al. Abstract 1012. Presented at: ASCO Annual Meeting; May 29-June 2, 2015; Chicago.

Chagpar AB, et al. N Engl J Med. 2015;doi:10.1056/NEJMoa1504473.

For more information:

Anees B. Chagpar, MD, MPH, can be reached at Yale School of Medicine Department of Surgery, PO Box 208062, New Haven, CT 06520; e-mail: anees.chagpar@yale.edu.

Disclosure: Chagpar reports no relevant financial disclosures. One researcher reports honoraria from BioTheranostics and Pfizer; a consultant role with Celgene and Clovis Oncology; and research funding from Foundation Medicine, Genentech and Merck.

Perspective

Michele A. Gadd, MD

New practice guidelines indicate that only tumor or ink requires re-excision for invasive disease, and I am not sure whether finding extra cancer in the tumor margins is a relevant finding, given the availability of good systemic treatment and radiation. Some surgeons perform a more generous lumpectomy with no shaved margins and others perform a slim lumpectomy at the tumor site and then shave the margins — in our past reviews, both have led to the same number of necessary re-excisions. Shaving margins does help orient the location of the close margin, leading to greater accuracy during re-excision and the removal of less overall tissue with this technique. It can also result in a better cosmetic outcome. However, I doubt that these findings will be practice changing.

Michele A. Gadd, MD

Massachusetts General Hospital

Disclosures: Gadd reports no relevant financial disclosures.