Emerging technologies for salivary biomarkers in cancer diagnostics

Abstract Cancer is the second most common cause of death worldwide. Early cancer detection can lead to a better prognosis of the patients. Conventional diagnostic methods are invasive, labor-intensive, and expensive, thereby making the detection process quite cumbersome. Therefore, there is an urgent need to develop noninvasive, rapid, and highly accurate tests for the screening, early detection, and prognosis of cancer. Further, saliva serves as a “mirror of the present health of an individual.” Biochemically, saliva is the mixture of electrolytes, peptides, proteins, DNA, coding and noncoding RNAs, exosomes, and microbiota. Numerous candidate molecules have been identified in the saliva as potential cancer biomarkers. Here, we review emerging technologies being used for the detection of various analytes such as mRNAs, microRNAs, metabolites, and microbiota in the saliva of cancer patients. Next, we describe various types of detection systems and progress towards the development of point-of-care biosensor devices for salivary biomarkers. Finally, we discuss challenges in the field of cancer salivary biomarkers.