Saliva can be used to diagnose whether someone has oral cancer and may also be a reliable indicator of other cancers and diseases, researchers said on Wednesday.

The research, carried out at the University of California at Los Angeles, provided the first proof that RNA biomarkers in saliva can be used to inexpensively detect cancer, said Dr. David Wong, study author and chairman of oral biology and medicine at the university.

The exploratory study, published in Clinical Cancer Research, showed that oral cancer was identified in nine out of 10 cancer patients.

“This is a new direction, using a non-invasive fluid to look for disease signatures, particularly in cancer,” Wong said, adding that new technology to rapidly analyze genes made this possible.

His team worked backward from saliva samples taken from patients with oral cancer to identify a combination of four RNA biomarkers, out of the 3,000 found in saliva, that provided a detectable signature for head and neck cancer - cancers of the mouth, tongue, larynx and pharynx.

RNA is the information carrier for genetic material. While DNA contains the instructions for producing proteins, RNA molecules carry the instructions into the cell’s machinery.

The UCLA study, funded by the National Institutes of Health, involved 32 patients with head and neck cancers and 32 subjects matched by age and gender who were cancer-free but had the same smoking history.

Using their saliva, researchers were able to discriminate the cancer patients from the control group, with a 91 percent accuracy rate.

Wong said that success rate had since inched up to 98 percent and a larger oral cancer study had been launched.