• 2/19/2006
  • St. Louis, MO
  • Dan Ferber
  • ScienceNow Daily News (sciencenow.sciencemag.org)

Human saliva contains telltale markers of breast cancer, diabetes, and an autoimmune disease, according to new results presented here today at annual meeting of the American Association for the Advancement of Science (which publishes ScienceNOW). If the findings are validated in clinical trials, spit tests could make up a new non-invasive way to quickly diagnose these diseases.

To form saliva, the salivary gland uses the soluble component of blood, known as serum, as its starting material. Physicians have dreamed for years of using saliva-based tests instead of blood tests. Among other conveniences, such a shift would remove the need for needles. Last year, oral biologist David Wong of the University of California, Los Angeles, and his colleagues reported progress toward one saliva test, showing that levels of four of the 3000 messenger RNA molecules typically found in human saliva were consistently elevated in oral cancer patients, but not in healthy patients. Recently, the UCLA team had an accuracy of 94% when attempting to diagnose oral cancer in 320 patients using these 4 RNAs as markers.

But oral cancer was just the beginning. At the meeting yesterday, Wong reported that his team has also examined the saliva from groups of 10 people with either type II diabetes, breast cancer, or Sjogren’s syndrome, an autoimmune disease that afflicts mostly women and destroys the salivary gland and pancreas. By using a gene chip to compare the salivary RNA of people in each disease group to that of 10 healthy people, the researchers found candidate RNA markers linked to Sjogren’s syndrome (26 RNAs), type II diabetes (126 RNAs), and breast cancer (103 RNAs). Each set of candidate markers now needs to be tested in larger groups of patients to see if it can be used to accurately diagnose the corresponding disease.

The researchers have also developed a prototype hand-held device that uses nanotechnology to test tiny droplets of saliva for the presence of specific saliva RNA molecules. Wong plans to find a company to help develop a hand-held device that could test saliva in 20 minutes for Sjogren’s syndrome, oral cancer, breast cancer, and type 2 diabetes.

“It’s very exciting,” says oral biologist James Melvin of the University of Rochester School of Medicine and Dentistry in New York State. “It means that potentially any disease will have biomarkers in saliva.”