US: Light to detect colon cancer

Short bursts of light from an endoscope could be a less invasive way for physicians to detect abnormal cells in the colon, according to bioengineers at Duke University in North Carolina. The finding could lead to improvements in the detection of dysplasia, abnormal cells with the potential to turn cancerous in the epithelium, which forms the lining of various tissues including the oesophagus and colon.

After demonstrating that light accurately detected pre-cancerous cells in the lining of the oesophagus, the bioengineers turned their technology to the colon and achieved similar results in a series of preliminary experiments.

Current biopsy techniques require physicians to take many tissue samples, and for some disorders of the colon these procedures can be disfiguring and life-changing. Instead of taking tissue samples, the new system would aim short bursts of light from the tip of an endoscope at locations suspected of having disease.

"When light is directed at these tissues, it scatters," said Adam Wax, an associate professor of biomedical engineering at Duke's Pratt school of engineering, who developed the device. The results of the team's preliminary experiments were reported online in the current edition of the Journal of Biomedical Optics.

"We can collect and analyse that scattered light, looking for the tell-tale signs of dysplasia. Significantly, the technique is non-invasive so no tissue is taken and no dyes or contrast agents are needed," Wax said.

In particular, the system is trying to spot characteristic changes within the cells of the epithelium. In the case of pre-cancerous cells, the nuclei are misshapen and the cells are larger than normal, and they scatter light in their own unique way.

"The important thing for clinicians is being able to detect these changes in the nuclei in cells just below the surface, which might not be detected by just looking at the lining of the colon through an endoscope alone," he said.

The technology is known as angle-resolved low coherence interferometry (a/LCI). In this process, light is shone into a cell and sensors capture the reflected light for analysis. The technique separates the unique patterns of the nucleus of the cell from its other parts and provides representations of shape changes.

"This approach could be the future of diagnosing dysplasia of the colon," said Dr Christopher Mantyh, colorectal surgeon at the Duke University Medical Center and a member of the research team. "The old-fashioned techniques we use haven't changed in years.

"This could be a real game-changer in how we detect, characterise and even treat pre-cancerous or cancerous lesions. For some gastrointestinal biopsies, the procedure itself has inherent risks such as bleeding or perforation, so a non-invasive technique could greatly improve a patient's quality of life."

In their experiments, the Duke team used the device on samples of colon removed from 27 patients suspected of having colon cancer. The researchers then compared the results obtained from their device to the actual findings made by pathologists and found that the overall accuracy of the device was 85%. The accuracy of the same technology was 86% during a recent clinical trial involving patients suspected of having Barrett's oesophagus, a precursor to oesophageal cancer.

Mantyh believes the new approach could be especially useful for people with inflammatory bowel disease because they tend to have a higher incidence of dysplasia in the colon. About 85% of all cancers begin within the layers of the epithelium in various parts of the body and Wax believes the new system could also work in such cancers as those of the trachea, cervix or bladder.