Breast Cancer Hot Topic: Clear Tumor Margins

VIDEO:  Doctors discuss the benefits of radiation therapy following a lumpectomy.
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Despite advances in breast cancer detection and treatment that have helped many women keep more of their own breast tissue, in about 40 percent of cases, U.S. surgeons re-operate to get a cancer-free margin.

The optimal size of the "clean margin" – a rim of healthy tissue beyond the tumor – was a hot topic at last week's annual meeting of the Society of Surgical Oncology in Orlando, Fla., especially in the most survivable breast cancer, ductal carcinoma in situ (DCIS).

As they debated surgical margins , the Journal of the National Cancer Institute published a review of 21 DCIS studies dating to 1970, from which University of Minnesota public health researchers concluded that surgeons should aim for "margins as wide as possible" for all DCIS. In an accompanying commentary, co-author Dr. Monica Morrow, chief of the breast cancer service at Memorial Sloan-Kettering Cancer Center in New York, called the study conclusion surprising and "a major change in the current standard surgical approach to DCIS."

Morrow, who on Friday became president of the Society of Surgical Oncology, said only five of the reviewed studies reported using margins of at least 10 millimeters (slightly more than a third of an inch). "Any net benefit of more widely clear margins on the overall health of women with DCIS would be extremely small or negligible," she said.

Morrow suggested research could be better directed toward "identifying those factors that result in the progression of DCIS to invasive cancer," which she called critical to tailoring treatment.

Although the rate of invasive breast cancer diagnoses has dropped since 2000, likely reflecting reduced hormone replacement therapy, the number of annual DCIS diagnoses has risen steadily to 60,000, from 4,900 in 1983, before widespread screening.

"It's not that it's become an epidemic," but that digital mammograms and MRIs are picking up more DCIS at a smaller, earlier stage, said Dr. Mehra Golshan, the director of breast surgical services at the Dana-Farber Cancer Institute in Boston, who was not involved in the JNCI study.

Regardless of whether a DCIS patient chooses lumpectomy followed by radiation, lumpectomy alone, mastectomy or nipple-sparing mastectomy, "survival is over 98 percent," Golshan said in an interview from the Orlando meeting. Rates of DCIS recurrence in the same breast range from less than 1 percent after mastectomy to 5 to 6 percent after lumpectomy plus radiation--which destroys microscopic cancer cells doctors cannot see, he said. With estrogen-positive DCIS, tamoxifen can further reduce that rate. As a result "you may not need an exact millimeter number to say what a clear margin is."

Target surgical margins vary, with institutions aiming for 2, 3, 5 or 10 millimeters of clean tissue, none demonstrated "specifically better than the others," Golshan said.

At Dana-Farber, "we like 3 mm. Massachusetts General across the street likes 2 mm. What our pathologists would consider 'clear' is a millimeter different." Both institutions do good surgery and care, he said.

Golshan called a 10 mm margin "way too much" for DCIS patients, who likely will live long enough to die from some other condition like heart disease. A 10 mm margin may take away so much of the breast -- as much as half -- that it defeats the goal of breast conservation, he said.

Surgical Trends Have Evolved Since the Radical Mastectomy

For decades, having breast cancer meant undergoing a dreaded radical mastectomy, the highly disfiguring removal of the breast, lymph nodes and chest muscles. But "bigger is better" got a successful challenge from Dr. Bernard Fisher, who led the landmark National Surgical Adjuvant Breast Project trial demonstrating lumpectomy was "as good as mastectomy."

Doctors improved lumpectomy by pairing it with radiation. They developed nipple-sparing mastectomies that particularly allowed younger women, smaller-breasted women, and those undergoing prophylactic surgery to undergo breast reconstruction using their own nipples and areolas.

Most recently, as digital mammography, MRI, and 3-D tomosynthesis have picked up tiny cancers that often went undetected in the past, some women are taking no chances "and we've kind of seen the pendulum shift back to more mastectomy," Golshan said.

So what's a newly diagnosed patient to make of all this?

Nurse-advocate Lillie Shockney, a two-time breast cancer survivor and administrative director of the Johns Hopkins Breast Center, says the key is bringing the patient into discussions balancing aesthetic concerns with her physical and mental wellbeing.

"I am a believer in the 2 mm margin," Shockney said. With the average woman's breast size a 34C, taking away 10 mm in every direction means "she's not going to have a lot of breast left," and could make her fear lumpectomy.

Low-grade DCIS cells closely resembling normal cells can elude sophisticated imaging, especially if diffusely spread along the milk ducts, leading to re-excision, she said. "You can get a clear margin and not know that there is more DCIS further up the duct, or further below the duct, and later on, doctors find more cancer."

That makes her adamant that patients clearly understand what's ahead. Surgeons must explain "the possibility that you may need a re-excision." If a woman insists she's "only going to go into the OR once," the surgeon must address the chances of an extensive lumpectomy or mastectomy and bring in a plastic surgeon to discuss reconstruction.

Shockney frequently talks petrified patients "off the cliff" by telling them their cancer likely has been around for years and there's time to think ahead. "I can say, 'you now know it's there, so your hair is on fire. I'm here with the fire hydrants to put the fire out, so we together can make good decisions, whether that be to take a little tissue out of (the breast) or rebuild you a new one."

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