The very small, preliminary study reviewed here shows that a new device is good at determining whether the outer edges (called margins) of the mass of tissue removed during lumpectomy are healthy or contain breast cancer. The device can be used during surgery and offers results in 5 minutes, compared to standard methods which take about a week.
In lumpectomy, a surgeon removes the cancer tumor and some of the normal tissue (the margin) that surrounds it. After lumpectomy, a pathologist carefully examines the tissue that was removed to see if cancer cells are present in the margins. Margins that are free of cancer are called "negative" or "clean." Margins that have cancer cells in them are called "positive."
Ideally, the surgeon would learn the status of the margins before the lumpectomy is completed, so as much tissue as needed could be removed until the margins were clean. Unfortunately, analyzing the tissue using currently available methods takes about a week. So in about 40% of lumpectomies, the margins are later found to contain cancer cells and more surgery is needed. This additional surgery is called a re-excision lumpectomy.
In this study, researchers used a new imaging device to analyze the margins of 55 tissue samples removed during lumpectomy. Most of the samples were from women diagnosed with early-stage, invasive breast cancer. Nine of the samples were from women diagnosed with DCIS (ductal carcinoma in situ). The researchers compared the results from the experimental device to the pathologists' reports on the margins.
In looking at the invasive breast cancer tissue samples:
In looking at non-invasive DCIS:
This experimental imaging device has tremendous potential. It could possibly eliminate the need for more surgery after lumpectomy because surgeons would know before they completed the procedure whether or not the margins were clean. Still, the device is experimental. While it looks promising, the accuracy is not yet reliable enough for doctors to use it with complete confidence. Improving the technology and more research will some day offer doctors a better, more immediate way to know whether margins are clean during lumpectomy.
Stay tuned to Breastcancer.org for the latest news on research that may lead to better ways to prevent, diagnose, and treat breast cancer.
SAN FRANCISCO, April 24 (MedPage Today) -- Intraoperative margins assessment may be possible with an experimental device that measures light scattering to determine tissue composition, researchers said.
The optical imaging device correctly identified 80% of pathologically positive or close margins and 67% of the pathologically negative margins, Quincy Brown, Ph.D., of Duke University in Durham, N.C., and colleagues found in a small pilot study.
The technology also identified eight out of nine margins with ductal carcinoma in situ, they reported at the American Society of Breast Surgeons meeting.
These preliminary results from 55 imaged specimens were promising given that standard pathological margin assessment usually takes about a week, said co-author Lee G. Wilke, M.D., also of Duke University.
The "research-grade" device takes about five minutes to analyze a specimen, Dr. Wilke said. If validated in further study, it could enable surgeons to correct margins if needed during the initial procedure and prevent revision surgeries, she said.
Shawna Willey, M.D., president of the American Society of Breast Surgeons, and moderator of a press conference at which the findings were presented, agreed that this is an area of unmet need for surgeons and patients.
Positive margins send women back to the operating room after about 40% of lumpectomies, Dr. Brown noted.
"Currently there are no rapid noninvasive imaging technologies for margin assessment," Dr. Wilke said. "In the operating room, the most simplistic is physician palpation of the lumpectomy specimen."
Mammography of the specimen has also been used, but it is only two-dimensional unless multiple views are taken, she noted.
In contrast, with this kind of X-ray or MR imaging, light in the visible spectrum cannot penetrate more than a few centimeters into solid tissue.
Although this makes it unsuitable for breast cancer screening, Dr. Brown noted that it's fine for margin assessment, which is typically measured to a depth of 2 mm.
Optical imaging technology can also be used at the point of care, is of modest cost, and can provide immediate results, the researchers noted.
The imaging device they developed is comprised of a broadband light source, an imaging spectrograph, and a CCD camera. The tumor specimen is placed in a box with a grid of holes to orient the imaging fiber optic probe.
The spectrographic data -- how much of the light is reflected, absorbed, and fluoresced by the tissue at each wavelength -- maps out the biochemical composition across the surface of the tumor specimen.
For example, a map of scattering characteristic of beta-carotene, a component of fatty tumor cells, reflects cell density, while scattering associated with hemoglobin reflects tissue vascularity.
The pilot study included 55 margins measured in surgically resected tumors of 48 patients who underwent breast-conserving surgery.
At the thresholds chosen for these biochemical markers of tumor presence, the researchers found that their device predicted positive margins with a P-value of 0.002 and an area under the curve of 0.77.
Dr. Brown said the sensitivity was 80% with a specificity of 70% for detecting positive margins in the cohort.
However, he said, the model is still being revised as further data come in from the full 100 patients they plan to study.
Dr. Wilke noted that the device will need to be tested for use with women who have had neoadjuvant treatment to determine how it is affected by the tissue alterations that occur with preoperative therapy.
Dr. Wilke reported being the principle investigator on a small business technology transfer grant given to Duke University to develop the device and being on the pending patent for it.
Primary source: American Society of Breast Surgeons Source reference: Wilke L, et al "Rapid non-invasive imaging of the biochemical composition in breast tumor margins" ASBS 2009.
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