New imaging technique may replace biopsies for early colon cancer detection

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Doctors may one day be able to detect early stages of colon cancer without a biopsy, using a new technique developed by researchers at the Stanford University School of Medicine in Stanford, Calif., and published online March 16 in Nature Medicine.

The imaging technology is one of many new ways of detecting cancers in the body in real time, said lead author Christopher Contag, PhD, associate professor of pediatrics and of microbiology and of immunology. Contag said he hoped it might be one of the first to be used routinely for early detection of cancer.

“Detecting colon cancers is just the first step,” said Contag. He predicted that similar techniques will eventually be able to find a wide range of cancers, monitor cancer treatment and deliver chemotherapies directly to cancerous cells in the colon, stomach, mouth and skin.

The difficulty in distinguishing cancer without a biopsy is finding a way to see which cells are cancerous while they are still in the body. Contag and his group said they succeeded in accomplishing this task.

The team reported that they found a short protein that sticks to colon cells in the early stages of cancer. Before screening a person, they spray that short protein attached to a fluorescent beacon into the colon. The protein then attaches to any cancerous cells and creates an easily visible fluorescent patch. The authors wrote that they then used a miniaturized microscope called Cellvizio, developed by Pennsylvania-based Mauna Kea Technologies and loaned to Contag, to inspect inside the colon and look for those revealing spots.

Not only did the researchers see fluorescent patches, they could make out the individual cancerous cells. The fine resolution could allow doctors to pick up the earliest possible cancers. Contag said it could also become a useful research tool for studying the small number of cancer stem cells that are thought to establish the eventual tumor.

In the initial trial with 15 patients, the technique detected 82 percent of the polyps that were considered cancerous by a pathologist, according to the researchers.

Contag said the next step is to work with some of the additional small proteins that they have found that also attach to cancerous cells. He said that a combination of those proteins will make the technique highly accurate.

Contag concluded that this technique, developed in part through the cancer imaging program at the Stanford Cancer Center, could also be adapted to detect cancers in the mouth, esophagus and stomach. In addition, real-time screening could be used as a way of assessing whether a chemotherapy regimen is working, according to Contag.

National Institutes of Health, the Doris Duke Charitable Foundation, the Stanford School of Medicine Dean's Fellowship and the John and Cynthia Fry Gunn Research Fund funded the research.