MAY 1, 2009--A novel optical imaging technique that quickly evaluates breast cancer tumor marginscould enable surgeons to review tumor-margin status during surgery--and reduce the current 40% resurgery rates. The approach was developed at Duke University(Durham, NC). Interim results of a pilot study evaluating the "optical intraoperative margin imaging" approach found that in 48 patients and 55 margins, the technique correctly identified 80% of the pathologically positive/close margins and 67% of the pathologically negative margins.
The study results were presented at this week's American Society of Breast Surgeons 10th Annual Meeting (April 22-29, San Diego, CA). Of the estimated 150,000 lumpectomies performed every year in the United States in the treatment of breast cancer, about 40% of cases require reoperation because of positive margins that are found postoperatively.
The technique takes advantage of the fact that light has distinct interactions with different biochemical substances and that cancerous and noncancerous cells have different biochemistry, says Quincy Brown, PhD, a postdoctoral researcher in Duke's Department of Biomedical Engineering. And according to Nimmi Ramanujam, PhD, associate professor of biomedical engineering, the technique reveals areas of high cell density and low fat content--these are suspicious of disease. Areas with low cell density and high fat content are expected to be negative for disease.
Breast specimens are physically evaluated in a Plexiglass box designed to expose and evaluate the margins. The approach captures images of different biochemical substances with varying colors and intensities, and uses mathematical models developed at Duke to characterize the underlying tissue composition in the margins of the tumors.
The researchers say the approach generates analysis of a 3 cm × 2 cm area in about 30 seconds.
The scientists have developed the technology in a portable format: a hand-held fiber-optic imaging probe connects to a computer console. "Our device consists of a broadband light source for illumination, an imaging spectrograph and charged-couple device camera for detection, and an imaging fiber-optic probe to relay light to and from margins of the tumor," the researchers say. The device is scheduled for clinical trials with a goal of commercialization.
In the study, the researchers evaluated tumor margins using optical intraoperative margin imaging and compared the findings with pathology results. Positive margins were found in 34 of the tumors with standard pathology, 13 of which were clearly positive and 21 of which were close (less than 2 mm) to the margin. Optical intraoperative margin imaging identified 27 of these 34 margins (80%) as positive/close, said the researchers. The technique correctly identified 14 of the 21 negative margins (67%). The mean invasive tumor size was 1.78 cm, and the specimens had up to 3 margins evaluated.