Spit Test Detects Cancer

Findings could lead to noninvasive diagnostic tools that examine saliva for signs of tumors.

Using only spit to differentiate people with head and neck tumors from a group of healthy subjects, researchers have shown that it's possible to screen RNA in saliva for cancer.

The work, by researchers at the University of California, Los Angeles Jonsson Cancer Center, is a proof of principle that could lead to new diagnostic tools and further studies using saliva to detect other cancers.

Researcher David Wong says that four RNA biomarkers were used to detect the presence of head and neck cancer with 91% sensitivity and accuracy.

"This is a new direction, using a noninvasive fluid for disease diagnostics, particularly in cancer," says Wong. "This is our proof of principle. We now hope to demonstrate the utility of saliva for systemic diagnosis of other diseases such as breast cancer."

Needle in a haystack

Cancer biomarkers are usually sought in blood serum and urine. Saliva contains the same biomarkers as blood, but at much lower levels.

Wong says that nanotechnology, which allows scientists to manipulate materials at atomic and molecular scales, helped the researchers uncover components of saliva and "changed the whole scene."

The researchers found that of the 3,000 RNA biomarkers in saliva, a combination of just four provided a detectable signature for head and neck cancer.

"This paper explores the translational utility of using saliva for cancer diagnosis," says Wong. "The work is good, but not good enough. Although we were able to identify the head and neck cancer patients with 91% sensitivity and accuracy, we missed one out of 10. With a larger study, we will move that specificity and accuracy closer to 100%."

Picking the sick

To test their approach, Wong and colleagues enrolled 32 subjects with head and neck cancers (mouth, tongue, larynx and pharynx) and 32 age- and gender-matched subjects without cancer but with the same smoking history. Using saliva, the researchers could discriminate those with cancer from the controls.

"We tested the hypothesis that distinct RNA expression patterns can be identified in cancer patients, and the differentially expressed transcripts can serve as biomarkers for cancer detection," the researchers write. "Moreover, using saliva as a diagnostic fluid meets the demands for inexpensive, noninvasive and accessible diagnostic methodology."

Wong and other researchers will next try to validate the study's findings in a larger study of about 200 people with oral cancer. (To participate, people with early and late stage head and neck cancer can call 1-888-798-0719.)

The research is reported in the journal Clinical Cancer Research.