A half million people are diagnosed every year with oral cancer. While other cancers are more prevalent, oral cancer is among the most dangerous with only a fifty percent five-year survival rate.
A major reason for this low rate is because this fast growing cancer is difficult to detect early — diagnosis comes far too often after the disease has already well advanced. In an effort to detect cancer earlier many dentists visually screen for oral abnormalities during checkups, especially patients over fifty, tobacco or heavy alcohol users, patients with a family history of cancer or a medical history of exposure to the sexually transmitted human papilloma virus, HPV-16.
If they detect an abnormality, the dentist often refers the patient to an oral surgeon or other specialist for a possible biopsy. In this procedure the surgeon removes a sample of the abnormal tissue, which is then examined microscopically for cancer cells. A biopsy remains the most effective way to diagnose oral cancer.
Because of the disease's aggressive nature, many dentists lean to the side of caution when referring patients for biopsy. As a result 90% of oral biopsies reveal no cancer. Reducing the number of biopsy referrals is highly desirable, especially for the patient undergoing the procedure. Tissue samples tend to be large to ensure complete detection of any cancer cells. Depending on the size and location of the sample, there may be a risk for loss of function or disfigurement.
A new screening tool using a sample of a patient's saliva could help reduce the number of biopsy referrals. Besides DNA, saliva also contains dormant genes called biomarkers that activate in response to the presence of a specific disease. This particular saliva test identifies those biomarkers for oral cancer if they're present.
A sample with a low score of biomarkers indicates no cancer present (with a statistical confidence of 99%). A medium or high score indicates cancer may be present, but only a biopsy can determine for sure. Using this test, dentists might be able to reduce the number of biopsy referrals and instead be able to employ watchful waiting in certain cases. Because of its simplicity and non-invasiveness, saliva screening could help identify oral cancer earlier.