Emerging non-invasively collected genomic and proteomic biomarkers for the early diagnosis of oral squamous cell carcinoma (OSCC)

Oral cancer is the sixth most common cancer worldwide ahead of Hodgkin's lymphoma, leukemia, brain, stomach, or ovarian cancers, with about 37,000 Americans being diagnosed annually. More than 90% of oral cancers are oral squamous cell carcinomas (OSCC). While the overall 5-year survival rate is about 50%, the survival rate when diagnosed early and treated as localized tumors is as high as 90%. Currently the gold standard for diagnosis of OSCC is early visual detection of a suspicious oral lesion followed by scalpel biopsy with adjunct histology. However, there are multiple limitations associated with biopsies: being invasive clinicians are hesitant to perform them, and patients may not agree to them due to the pain and discomfort of the procedure; the following histology requires expert analysis and is therefore expensive; and issues such as under-sampling add uncertainty to diagnosis. An ideal alternative to scalpel biopsy would be non-invasively collected samples containing biomarkers which can distinguish between oral pre-malignant lesions (OPMLs) and OSCC, and potentially predict the transition from pre-malignancy to malignancy. Methods for sampling and discovering biomarkers of OSCC in a non-invasive fashion have been emerging, including those focusing on whole saliva and cells and other specimens collected directly from oral lesions. These samples are ideally suited for system-wide analysis using genomic and proteomic technologies for biomarker discovery. Here, we describe the current state of the clinical diagnosis of oral cancer, with an emphasis on emerging genomic and proteomic strategies seeking to identify non-invasively collected biomarkers that could improve the early diagnosis of OPML transition to OSCC.