The finding that reoperation rates after breast-conserving surgery are higher for women diagnosed with ductal carcinoma in situ (DCIS) compared with invasive breast cancer (IBC) is not new, but it reinforces the message to clinicians about counseling patients so that they understand that further surgery may be required.
Reoperation comes with significant physical, psychological, cosmetic and financial challenges, note Danish researchers reporting the latest study on reoperation risks. .
The study, by Linnea Langhans, MD, from Rigshospitalet at the University of Copenhagen, Denmark, and colleagues, was published on December 21 in JAMA Surgery.
The team reviewed data on 4500 women with IBC or DCIS who underwent wire-guided breast-conserving surgery from January 1, 2010, through December 31, 2013. These data were retrieved from the Danish National Patient Registry and were cross-checked with the Danish Breast Cancer Group database for preoperative diagnoses, making it possible to exclude 382 patients who underwent wire-guided diagnostic excisional biopsies. Mean age of the cohort was 60.9 years.
After the first re-excision, positive margins were still present in 97 patients (16.4%).
A total of 202 patients underwent mastectomy as the first or second reoperation, and the remaining 523 patients underwent one or two re-excisions. Type of reoperation did not differ between patients with DCIS and patients with IBC.
Overall, the Danish researchers found a reoperation rate of 17.6% (14.4% re-excisions and 3.2% mastectomies).
Although this rate is slightly lower than shown in previous studies, this team also found that patients with DCIS also had a reoperation risk that was 3 times higher than that in patients with IBC (37.3% vs 13.4%; P < .001).
The risk for repeated positive margins was also significantly higher in patients with DCIS vs those with IBC (unadjusted odds ratio, 2.21; P < .001).
The findings underscore the importance of precision localization of nonpalpable DCIS lesions, say the investigators.
The margins of DCIS lesions are not well defined, and it is difficult to determine how far they extend into the breast, they comment, adding that this "probably accounts for the high rate of reoperations seen in patients with DCIS vs those with IBC."
Better preoperative imaging could benefit a small percentage of patients who could be allocated to undergo immediate mastectomy instead of breast-conserving surgery, they suggest, although they add that such a subgroup was not identified in the study.
"The widespread use of mammographic screening will increase the number of patients diagnosed with DCIS," they note.
Findings Are Not New
These findings are not new," says Cheng-Har Yip, MBBS, clinical professor in the Department of Surgery at the University Tunku Abdul Rahman and professor emeritus of surgery at the University Malaya in Kuala Lumpur, writing in an invited commentary.
Previous studies have shown a similar result, although the difference was not as high as in the current study, Dr Yip commented to Medscape Medical News in an email.
The large difference in the reoperation rates in this study "is probably because the rate of reoperation in patients with IBC is lower than in other reported studies," he suggested. He noted that a previous study (JAMA. 2009;302:1551-1556) found a smaller difference in the reoperation rates, although the rates were still higher for DCIS (30.7%) than for stage I IBC (23.7%) and stage II IBC (24%).
"It is well known that reoperation rates can vary between hospitals and between different surgeons," Dr Yip told Medscape Medical News. "What is important is that surgeons counsel patients about the risk of reoperation."
Dr Yip also acknowledged that in the past there has been a lack of consensus on positive margins. However, he noted that 2014and 2016 consensus guidelines issued by the Society of Surgical Oncology/American Society for Radiation Oncology/American Society of Clinical Oncology have "confirmed that for IBC, no ink at margins is sufficient, and for DCIS, a 2-mm margin is recommended."
"We also have to take into account the size of the lesion, the age of the patient, and other features, such as grade of DCIS," he said.
With counseling, patients may choose a mastectomy rather than a lumpectomy, especially when immediate reconstruction has become the standard of care, said Dr Yip, noting that studies show that when patients are more involved in decision-making, rates of mastectomy increase.
"I use a patient decision aid that is designed to help patients with very early breast cancer decide between breast-conserving surgery or mastectomy," he explained.
The decision aid lists the pros and cons. A higher local recurrence rate, a 1-in-5 risk for a second operation, and the need for radiation therapy after breast-conserving surgery fall into the "cons."
Counseling should never be directive unless the patient has multifocal disease and a breast-conserving procedure is not an option, he said.
"I would always counsel for breast-conserving surgery rather than mastectomy, but after studying the pros and cons, the patient may decide against breast-conserving surgery but it is her choice, not the surgeon's," he said.
Dr Yip admitted that he sometimes feels "a sense of relief" when a patient chooses mastectomy.
"Until the histopathology result comes out, which can take up to a week, both surgeon and patient are on tenterhooks, wondering whether reoperation is needed," he said.
Innovative trials on emerging new technologies, such as mass spectroscopy or bioimpedance, may reduce the reoperation rate, he noted, but they are experimental and not currently available.
Until then, it is difficult to counsel against breast-conserving therapy unless there is extensive microcalcification on mammography, Dr Yip told Medscape Medical News.
If he suspects a patient won't respond well to possible reoperation, Dr Yip considers intraoperative margin assessment by frozen section, even though it can be difficult to perform in DCIS, increasing operating time and costs and requiring an experienced pathologist.
"An intraoperative specimen mammography, especially when DCIS presents as a cluster of microcalcifications, can determine if all the microcalcifications have been removed with a clear margin."
This study was funded by the Danish Cancer Society and the Danish Cancer Research Foundation. The study authors and invited commentary author have disclosed no relevant financial relationships.
JAMA Surg. Published online December 21, 2016