Researchers Study 'Natural' Screen For Cancer

February 06, 1998

A team of researchers at Simon Fraser University is shedding new light on cancer detection and treatment.

Engineering scientist Andrew Rawicz and two researchers from the University of Kiev are testing the illuminating qualities of an herbal extract called hypericin, which they say is quickly absorbed by cancerous cells. Taken orally or applied topically to the skin, hypericin shows up as a red spot when a patient is "illuminated," with blue filtered light. The substance intensifies on areas where cancer is present, even in its earliest stages.

"Tumors are greedy," says Rawicz. "Cancer cells grow fast and eat more, and tend to accumulate more of the hypericin -- even 10 times more than normal cells -- so once it is absorbed, we can illuminate the patient in a dark room and see these localized red spots. We can say, 'this is where the cancer is.'"

The method is being tested in eastern Europe, with encouraging results, say researchers. Rawicz "imported" the concept with his two colleagues, Ivan Melnik, a professor from the State University in Kiev, and PhD student Sergiy Dets. The research is supported by his own company, Andrew Engineering Inc., an SFU spin-off company.

Researchers have set up a makeshift lab in a 10-by-10-foot darkroom on campus. Costs are cut by using a little imagination -- a modified theatre stage light provides the filtered blue light, for example. A highly sensitive camera capable of reading only the light produced by the hypericin transmits an imageback to a computer screen for closer scrutiny.

"Hypericin gives us a very natural way of screening for various types of cancer," says Rawicz, whose lab produces much of its own hypericin from branches of the herb, St. John's Wort. Rawicz says there are almost no side effects from the use of hypericin, which costs much less than other substances created synthetically to track cancer cells. "Patients who take these other substances can become photo toxic when in sunlight, for up to one month," explains Rawicz.

"Hypericin actually has a 10 times higher phototoxicity -- but it lasts only 10 hours."

The researchers have run tests on dogs at a local veterinarian clinic and were able to detect one case of cancer. They plan to continue their work on hamsters.

Once cancer has been identified, "photodynamic-treatment " once again, using light rays to target the cells can help kill the disease. An orange light forces hypericin to release oxygen "singlets" and decompose cancerous cells.

A second study involves the use of a "diffused spectroscope" to study melanoma, or skin cancer. Researchers developed the device, which is patented, to "inject" light into skin, where it is modified, then returns. Analysis of the light that comes back provides key information about the skin, says Rawicz. The project is being funded by a grant from the B.C. Science Council.

Measuring light is the key to another of Rawicz's group projects -- a dental color analyzer, which he expects to soon produce commercially. The analyzer allows for a precise match of dental material for reconstructive work on teeth, which, like skin, are translucent.

"Our impression of color is not only based on the reflection of light, but on the process that occurs when light enters the tooth it bounces and only partially comes out. We found a way to measure only the light which exits. In the same way, we can precisely measure the pigmentation of the skin and more easily diagnose the presence of melanoma."

Rawicz says all of the group's projects grew from research towards the development of an artifical eye, which he began several years ago. "We've simply taken what we've learned about vision, perception and color and applied those things to other areas," says Rawicz, whose company is a founding member of the Optical Processing and Computing Consortium of Canada. Rawicz has also been instrumental in the creation of a laser positioning system, which provides surgeons with improved knowledge of where and how they aim laser surgical tools during eye surgery.

CONTACT: Andrew Rawicz, 604-291-3819
Marianne Meadahl, media/pr, 604-291-4323

Simon Fraser University

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