• 3/31/2005
  • Houston, TX
  • CancerWise (www.cancerwise.org)

New Devices May Help Detect Tumors Earlier

In the hope of finding an often-devastating cancer before it has a chance to develop, researchers are designing a series of probes that will literally highlight suspicious lesions in the mouth that may harbor fledgling tumors.

These devices — a “scanner” that first bathes the mouth with light to pick out problem areas and a follow-up probe that shines a concentrated diagnostic beam on the lesions— are scheduled for testing at M. D. Anderson this spring and summer.

If they fare well, the device designers foresee a time when community dentists or physicians turn to the probes to help screen for spots that can be difficult to pick out by observation alone.

“I can’t always tell which mouth lesions might be precancerous. They can be tiny white, pink or red areas that are really hard to tell apart from normal tissue,” says Ann Gillenwater, M.D., an associate professor in M. D. Anderson’s Department of Head and Neck Surgery. “Now, our only choice is to biopsy an area that looks suspicious, and this can be more invasive than is necessary.”

“More research needs to be done, but with these devices it may be possible to find oral cavity cancers when they are at their most treatable,” says Gillenwater, who has been conducting studies on the technology for several years. “When found later, as many of these cancers are, the effects of surgery and radiation treatment can impact a patient’s quality of living, if not their lives.”

Cancer reflects light differently

We don’t always know why people develop cancer of the mouth, also known as oral cancer. Smoking and smokeless tobacco are strong risk factors, but the cancer also develops in a number of nonsmokers. Unfortunately, it is most often diagnosed at an advanced stage, when it is difficult to treat.

But like some other cancers, those of the mouth share a feature that offers a chance at early detection — they interact with light differently than normal tissue. Collagen and other molecules found in the lining of the mouth (and in other sites) fluoresce naturally. That is, they glow when bathed in certain wavelengths of light. For reasons that aren’t completely understood, the fluorescent light emitted from cancerous and precancerous tissues is less intense.

“It has been known for a century that cancer cells have different optical features, but the trick has been that these differences have been hard to pick up,” Gillenwater says. “Now, computing and optical technology is at the point where we can try to solve this.”

Gillenwater, working with Rebecca Richards-Kortum, Ph.D., an electrical engineering professor at The University of Texas in Austin, has designed a two-step system that uses state-of-the-art equipment to assess minute changes in fluorescence. It is the same kind of technology being developed by Michele Follen, M.D., Ph.D., a professor in M. D. Anderson’s Department of Gynecologic Oncology, for the detection of cervical cancer. Others also are looking into whether such devices can find breast, colon and bladder cancer.

Moving into testing

Development of the oral cancer probes is being supported with funds from the National Institutes of Health. Both hook up to computers that analyze differences in light waves from normal and precancerous or cancerous tissue.

The first device is a multispectral digital microscope known as the “MDM scanner” that is still being developed. Researchers have tweaked an existing dental microscope to churn out different wavelengths of light, and they are now figuring out which wavelengths of light are best at generating fluorescence in the target tissue. Researchers want to launch a small trial to test the scanner later this year.

The second device is an eight-inch, pen-like probe designed to be placed directly on areas that the scanner detects as suspicious and measure fluorescence emitted. It also uses what is known as “reflectance spectroscopy” to measure the wavelengths of light bounced off cells at the surface of mouth. The probe has been more extensively tested and a new trial is slated to begin shortly. In this test of more than 100 patients referred to M. D. Anderson because of a suspicious lesion, researchers will use the probe before a surgical biopsy, and then will compare results of the probe to the outcome from the biopsy.

“The notion that a physician might be able to pick up a precancerous lesion with just a harmless beam of light is very exciting to us,” Gillenwater says.