Rates of re-excision and conversion to mastectomy after initial lumpectomy in women with early invasive breast cancer dropped dramatically after the release of a 2014 consensus guideline recommending a "no ink on tumor" minimal negative margin.
The finding comes from a population-based cohort survey study presented here at the American Society of Clinical Oncology (ASCO) 2017 Annual Meeting and simultaneously published online on June 5 in JAMA Oncology.
The study looked at 3729 women who underwent initial lumpectomy between 2013 and 2015 and found that the rate of final lumpectomy increased by 13% while surgery after lumpectomy fell by 16%, and unilateral and bilateral mastectomy decreased as well (P = .002).
"These results demonstrate that evidence-based clinical guidelines can accelerate practice change that reduces overtreatment in cancer care," lead study author, Monica Morrow, MD, chief of breast surgery at Memorial Sloan Kettering Cancer Center in New York City, said at the meeting. "What we're seeing clinically corresponds to surgeon attitudes about what constitutes an adequate margin," she said.
Dr Morrow is also immediate past president of the Society of Surgical Oncology (SSO) — which developed the guideline in conjunction with the American Society for Radiation Oncology (ASTRO) — and cochair of the guidelines consensus panel.
"It appears that by reducing second surgical procedures, you can actually increase the number of women who are interested in having a lumpectomy and who end up retaining their breast," Dr Morrow said in a JAMA Oncology author audio interview.
For the study, women who had stage I and II breast cancer were identified from the Surveillance, Epidemiology, and End Results registries in Georgia and Los Angeles County, California. Cases of bilateral disease or ductal carcinoma in situ were excluded. The pathology reports of patients who underwent a second surgery and 30% of patients who underwent a single surgery were reviewed and patients and their surgeons were surveyed. Median age was 61 years.
At the beginning of the study in April 2013, immediately before the release of the guideline, the rate of breast-conserving surgery (BCS) was 52%.
By April 2015, after the guideline was published, the lumpectomy rate had increased to 65% and was accompanied by a decrease in both unilateral mastectomy, which fell from 27% to 18%, and a decrease in bilateral mastectomy, which dropped from 21% to 16%. Re-excision rates fell from 21% to 14% and conversion to mastectomy in women who attempted lumpectomy decreased from 13% to 4% in that time.
As previously reported by Medscape Medical News, "the guideline establishes 'the use of no ink on tumor as the standard for an adequate margin in invasive cancer' and adds that the 'routine practice of obtaining wider negative margins than no ink on tumor is not indicated.' "
Importantly, the guideline was created to address growing concerns about overtreatment in cancer care — particularly breast cancer.
Breast cancer exemplifies these concerns because most newly diagnosed patients with a favorable prognosis are treated with multiple modalities for which the benefit of each treatment may be small, but the burden is cumulative and substantial," Dr Morrow and colleagues say.
There was no shift in patients' attitudes toward additional surgery, as evidenced by the unchanging 67% rate of initial lumpectomy throughout the study period.
However, surgeons' opinions about what constituted an appropriate BCS negative margin changed significantly following the guideline's release. Of the 342 surgeons surveyed between April 2015 and May 2016, 69% said they endorsed a margin of no ink on tumor to avoid re-excision in estrogen receptor–positive, progesterone receptor–positive cancer and 63% said they would support it for estrogen receptor–negative, progesterone receptor–negative cancer.
Before this, differing opinions on the best negative margin width in lumpectomy resulted in increasing numbers of BCS patients returning to the operating room for re-excision lumpectomy and/or mastectomy, with rates ranging from 23% to 38%. In some cases, unilateral disease was being treated with bilateral mastectomy, Dr Morrow said, adding that, "This is a dramatic change."
In 2005, she pointed out, her group reported results from a study showing that just 10 years ago, only 11% of surgeons would accept the same margin width as adequate. Now, "high-volume" surgeons treating more than 50 patients with breast cancer a year are the most likely to accept the new margin: Eighty-five percent said they endorsed it compared with 55% of surgeons treating 20 or fewer patients with breast cancer a year (P < .001).
"It's now been more 35 years since the prospective randomized trials have demonstrated that survival after breast-conserving surgery and whole-breast irradiation is equivalent to survival after mastectomy," Dr Morrow noted. "And after those trials were published, we saw steady increases in the rates of breast-conserving surgery until about 2005/6. At that point, breast-conserving surgery rates began to decrease, accompanied by a rise in bilateral mastectomy for women with unilateral breast cancer."
The latter was particularly surprising, she added, because modern adjuvant systemic therapies have kept rates of contralateral breast cancer as low as 5% to 6% at 20 years.
Concerns about why women with early-stage breast cancer would choose to undergo more extensive surgery, including breast reconstruction, when they could keep their own breast, have fueled the debate about overtreatment in breast cancer, Dr Morrow said. "What is the cause of all these mastectomies and, in particular, bilateral mastectomies?"
In a word? Patients.
Even though it was originally thought that surgeons were simply not counseling their patients appropriately, Dr Morrow's group also demonstrated in previous work that patients have been driving these "bigger surgery" decisions. "It turns out that when the patient self-identifies as the decision-maker, the mastectomy rate is about 25%," she explained. "When the patient identifies the surgeon as the decision-maker, the mastectomy rate is only about 5%."
To reduce overtreatment, clinicians need to work on the shared decision-making process with patients by developing ways to communicate information that patients can better understand. For starters, treatment that is medically inappropriate needs to be distinguished from a patient choosing mastectomy over lumpectomy after being told that the survival rate between the two is equal.
"Is that overtreatment?" Dr Morrow asked. "I think that while many of us would say 'Yes, it probably is,' what we need to focus on are ways to better help patients understand the decision-making process at the time of new cancer diagnosis when they're consumed with torrents of information, fear of death, and that sort of thing."
The same problems exist when a patient opts for medical oncology treatment that has a 2% to 3% chance of benefit in an attempt "to do everything," Dr Morrow pointed out. "Does that constitute overtreatment? Where do we draw the line about how much benefit a treatment needs to have in order to make it worthwhile? Clearly, patients draw that line in different places."
Despite a dramatic change in postlumpectomy rates, the study shows that 41% of additional surgeries are still performed in women with negative margins. This suggests that more widespread adoption of the guideline is needed, Dr Morrow said.
"It's important to recognize that some patients with negative margins will continue to require re-excision, but many do not. I think our findings about the relationship between surgical volume and acceptance of this margin indicates that we need to reach out with these results not just to breast specialist surgeons but also to general surgeons who perform the bulk of breast cancer surgeries in the United States."
Limitations of the study include the fact that it didn't directly show causality between the guidelines and changing rates of postlumpectomy surgery. "What we're seeing is not a reflection of a general change in attitudes related to overtreatment in breast cancer surgery," Dr Morrow said. "It appears to be specific to patients with invasive breast cancer. But we did not directly address causality so we can only draw these inferences."
This study was funded by the National Cancer Institute (NCI). Dr Morrow discloses that she is the associate editor for reviews and CME of JAMA Oncology. No other study authors have disclosed any relevant financial relationships.