Spit Test Spots Oral Cancer
Saliva holds gene 'signature' that warns of early disease, study finds
THURSDAY, March 9, 2006 (HealthDay News) -- Researchers may be within spitting distance of a reliable, saliva-based early detection test for oral cancer.
"It's nothing more than having someone spit. And 24 hours after the sample is mailed in, that information could be known to the individual -- whether you're at risk of having oral cancer," said study senior researcher Dr. David T. Wong, director of the Dental Research Institute at the University of California, Los Angeles.
His team presented its findings Thursday at the American Association for Dental Research annual meeting, in Orlando, Fla.
According to the American Cancer Society, each year more than 31,000 Americans are diagnosed with some form of oral cancer, and more than 7,000 people die from the disease. Smoking and the use of smokeless tobacco products, as well as excessive drinking, are both risk factors for oral malignancies.
According to Wong, early detection is key to beating oral cancer.
"The later you detect it, the more dreadful the outcome," he said. "For example, someone who has what we call stage 3 disease -- there are stages one through four -- has only a 20 percent chance of survival. But if you detect that person's disease at stage one, he'll have a 90 percent chance of survival over five years."
Regular, thorough oral exams by a trained professional can spot lesions early on, but "not every dentist or health-care provider does a full oral heath exam," Wong said.
That's why he and other researchers are working on a noninvasive, saliva-based early detection test for oral cancer. For example, researchers at the Forsyth Institute in Boston announced last year that a test they are developing, which focuses on malignancy-linked bacteria, was 80 percent accurate in spotting oral cancers.
The UCLA test is different. It relies on bits of genetic material called messenger RNA. Four RNA molecules, in particular, appear to be a "signature" for the presence of an oral malignancy.
In studies involving saliva samples from more than 300 oral cancer patients and healthy controls, "the four [RNAs] in combination could have a sensitivity and specificity for oral cancer of over 90 percent," Wong said.
The test itself is as simple as having patients spit into a special cup containing a preserving solution, he said. The sample is then sent off to a lab for quick analysis. If a test turns up positive, "that person would be brought back for an examination of the oral cavity to find a lesion," Wong said.
While these results are promising, the participants studied all live in and around the Los Angeles area. Dr. Len Lichtenfeld, deputy chief medical officer at the American Cancer Society, said the test may someday become a reality in doctor's offices around the nation, "but first you have to confirm that the standardization [of the test] works beyond the patients here."
"It needs to be replicated test to test," he said. "So the next step, obviously, is taking it into the clinic and looking at large numbers of individuals."
Wong said he's working with the U.S. National Cancer Institute to set up just this type of broad clinical trial, with results expected in two to three years.
And he stressed that his team's work with oral cancer is just the tip of the iceberg.
"We're diversifying into other high-impact diseases to demonstrate the versatility and value of saliva as a diagnostic fluid," Wong said. Most promising: A spit test for the early detection of breast cancer.
"We're in the discovery phase, and we have been very encouraged by the signature pattern of these molecules in the saliva of breast cancer patients," he said. "That's the same pathway we took with oral cancer."
For more on oral cancer, visit the American Cancer Society.