A new saliva test could save thousands of lives by detecting cancer early will begin clinical trials this year. Testing of the technology has already shown promising results, proving the ability to detect biomarkers for a specific form of lung cancer.
Research published in the International Journal of Oral Science suggests that saliva is a promising biomarker source. Being able to detect a disease using this biological sample would, firstly, provide us with an inexpensive and non-invasive diagnostic method. As such, cost-effectiveness analyses support the use of saliva for detecting diseases such as cancer. Furthermore, saliva studies have certain advantages over conventional blood tests such as simplicity in obtaining the sample, safety and ease of storing these samples.
But what is the composition of saliva? Can it vary over time and hence influence the results of possible diagnosis methods? A paper published in Physiology Research explained that saliva is more than just a fluid produced by the salivary glands. In addition to its high water content, it also contains proteins, hormones, lipids, sugars, and ions, whose concentration can be affected based on the type and duration of the gland stimuli, the flow rate, and our circadian rhythm. But saliva also contains epithelial cells, bacteria, and food debris, which affect the proteome of saliva. Today we know that amylase, carbonic anhydrase, mucins, and cystatins are some of the most important enzymes found in saliva, although the complete list would amount to over three thousand proteins.
Proteomics research has made it possible to prepare a first profile of the biological molecules that can be found in saliva, so we can now compare healthy people and cancer patients. Knowing which molecules can act as biomarkers is a very important first step. Scientists at the University of California have set up the first saliva proteome knowledge base, a significant advance in a new discipline better known as salivaomics. As shown in the figure below, over the past six years a number of biomolecules have been identified in saliva that can be used to detect local and systemic diseases. They include diabetes, dental problems, breast cancer, and AIDS.
Technology could help diagnose hard-to-detect cancers
Cancer Council Australia chief executive Professor Sanchia Aranda said while more still needs to be learned about the technology, results have so far been encouraging. They do hold promise for being able to detect cancers early before either the symptoms or signs that the patient would pick up.
“Molecular diagnostics, such as this saliva test, are really important developments for cancer detection, largely because by-products of the cancer development process circulate in the blood and in this case in saliva, and can be used to pick up cancers before they would cause any problems for the individual,” she said.
“But like any other screening test, we need to know that they’re sensitive and that they’re reliable but, importantly, that they would alter the natural history of the disease.
“Therefore meaning that they would perhaps reduce the amount of death or disability that the person incurs other than if it had been diagnosed a different way.”
Professor Aranda said the potential benefits were for early detection of cancers that are currently difficult to detect.
“Importantly, they do hold promise for being able to detect cancers early before either the symptoms or signs that the patient would pick up, and we know that curing cancer really rests on that whole question of early diagnosis,” she said.
“And so that is really where they hold promise.”