Real-time 3-D analysis of breast cancer biopsies

Nov 14 2007

A sophisticated microscope that offers a "real-time" 3-D analysis of tissue samples might, in the future, reduce the number of needle biopsies traditionally needed from women suspected of having breast cancer, according to recent research published at Georgetown University Medical Center's Lombardi Comprehensive Cancer Center.

Such an instant test would mean that physicians could immediately tell if they have collected adequate samples of breast tissue and limit the number of repeat biopsies, said the investigators, whose study appeared in the September/October issue of the Journal of Biomedical Optics.

Currently, physicians extract 6-8 tissue samples during a needle biopsy procedure to ensure proper sampling of the area of concern. In addition, at least one day is required to prepare the samples for analysis using traditional methods. The new technology is designed to limit patient discomfort and anxiety.

“With this microscope, we can tell instantly whether we have cancer cells or not, or what kind of cells we are looking at, whether they are fat, structural, or epithelial cells that line breast milk ducts—all of this could give us a great advantage in treating breast cancer,” said the study's lead investigator, Maddalena T. Tilli, PhD, a postdoctoral fellow in the laboratory of Priscilla Furth, MD, at the Lombardi Comprehensive Cancer Center, part of Georgetown University Medical Center.

“This tool could perhaps be used at the bedside to not only reduce the number of biopsies that we take from patients, but which could possibly be used during an operation to make sure surgeons have removed all cancerous tissue,” said Furth, the study's senior investigator and a professor of oncology at Georgetown.

The technique is fairly simple. A reflectance confocal microscope reflects near-infrared light off multiple mirrors through tissue, then records the scattering of light. “The idea behind this is that certain structures in the cell will look different based on the pattern of light reflectance,” Tilli said. To highlight the nuclei in the cell, the researchers douse the tissue in a 5 percent solution of acetic acid, the major component in vinegar. “The acid condenses DNA in the cell, and based on where the DNA is located, you can tell what kind of cells these are,” she says.

The whole procedure takes 10 minutes or less from the time the tissue is removed, researchers say. Traditionally, biopsy tissue is “fixed” in a solution of formaldehyde to preserve it, then it is embedded in wax and, finally, sliced and stained. While this technique reveals a lot of detail about cells, it takes a long time to prepare, Furth said. “Now we can combine both of these methods,” she added. “We can sample biopsy tissue instantly with microscopy and then use the same sample to fix it in the normal way to assess the type of cancer a woman has.”

Funded by grants from Susan G. Komen For the Cure, awarded to Georgetown breast cancer oncologist and principal investigator Minetta C. Liu, MD, Tilli and Furth adapted the technique for analyzing reading breast tissue. Reflectance confocal microscopy also is currently being used on a limited scale to assess skin conditions such as melanoma.

Tilli and Furth first determined that the mechanism worked well to image all stages of normal mammary gland development in animal models. Then they examined 25 breast needle biopsies taken from 16 patients to look at whether reflectance confocal microscopy can assess, in real time, the content of epithelial cells and supporting structural “stromal” cells as well as the presence or absence of cancer, in comparison to the same biopsy tissue prepared in the traditional way.

“We found that we can tell the difference between cells, and we can determine if a cell is cancerous, but we can't yet tell precisely which type of cancer is present,” Tilli said. “Another advantage this procedure offers us is that we can look at different layers in the tissue, unlike the traditional method, which slices tissue apart.”

The researchers are currently studying use of new contrast agents and other methods to increase detection and resolution of cancer cells.