The current procedures for oral cancer diagnosis are Biopsy and histopathological examination, Vital staining, Biomarkers, DNA ploidy, brush biopsy and optical techniques.
Biopsy and histopathological examination is the current golden standard of oral cancer diagnosis where a large piece of tissue from the suspected lesion and area surrounding it is taken and is analyzed for dysplasia and cancer. However the process is very painful and takes several days for diagnosis.
Vital staining is a technique used to stain living cells in order to highlight probable dysplastic areas before a biopsy is done. Vital tissue staining via topical application of toluidine blue (tolonium chloride), a metachromatic dye that preferentially stains cells with elevated DNA content, has been utilized for decades to assist in identifying oral cancer sites and/or delineating margins for excisional biopsy. Although toluidine blue staining yields high sensitivity in detecting SCC malignancies, its usefulness may be limited in characterizing mild-moderate epithelial dysplasia found in oral pre-malignant lesions.
Recent advances in molecular techniques has helped examining for abnormal protein expression to unravel complex cellular mechanisms associated with tumorigenesis revealing a number of molecular markers, or biomarkers, related to oral cancer initiation and progression. Biomarkers have been utilized in a range of clinical settings including screening, diagnosis, staging, prediction of treatment response, and monitoring of treatment and recurrence.
DNA ploidy is the measurement of nuclear DNA content. This may provide a surrogate measure of gross genetic damage and this could act as a surrogate for individual molecular markers. DNA ploidy can be measured fairly simply with automated image cytometry of nuclei obtained from routinely processed tissue samples.
The brush biopsy uses a small nylon brush to gather cytology samples then sent for computer scanning and analysis (Oral CDx) to identify and display individual cells. If suspect cells are identified, a pathologist then examines them to determine the final diagnosis and, in samples judged to be cancerous, a printout of the abnormal cells from the computer display and a written pathologist's report are returned to the clinician with the recommendation that a positive result be followed with a conventional incisional biopsy. The technique has proved rather controversial, with concern largely related to the question of false negative results.