The UCLA team collected saliva and blood from 32 patients with primary oral squamous cell carcinoma and 40 breast cancer patients, and matched each with saliva and blood from otherwise normal subjects. New techniques were developed to halt RNA degradation so the scientists could recover as much mRNA as possible for their samples. In all, the new techniques allowed the scientists to harvest up to 10,000 types of human mRNA from saliva, setting up a comparison test between cancer patients and the normal subjects based on analysis of their genetic "profiles."
"Both serum and saliva exhibited unique genetic profiles," said Wong. "The risk model yielded a predictive power of 95 percent by using only the salivary transcriptome samples and 88 percent by using only serum transcriptome samples for oral squamous cell carcinomas," said Wong. "For oral cancer, salivary transcriptome has a slight edge of that of serum transcriptome analysis."
Future research not only will involve a larger sample of cancer patients to refine prediction models, but also will include studies involving precancers and other difficult to detect cancers such as ovarian and pancreatic cancers.
"In my mind the biggest hurdle stems from the fact that salivary nucleic acids or protein markers might be influenced by eating, drinking, smoking, diet or oral hygiene," said Wong. "So our goal is to provide the optimized and standardized protocol to assure consistent results."
The studies are supported by grants from the U.S. Public Health Service (National Institute of Dental & Craniofacial Research) and the UCLA Jonsson Comprehensive Cancer Center to David T. Wong.