Commentary—Screening Aids for Cancer of the Mouth: Are They Really Aids?

The Journal of the American Dental Association recently published an updated review of the techniques for screening people for oral cancers.

As part of a comprehensive dental examination, dentists, of course, look for cavities and gum disease, but they also examine people to detect potentially cancerous growths in the mouth. There are many causes of oral growths, but cancer of the mouth is a very dangerous one. Cancer of the mouth develops in about 40,000 people in the US each year and can be fatal. Infection with the human papilloma virus (HPV) and use of alcohol and/or tobacco increase the risk of mouth and upper throat cancer.

Dentists typically use a bright light and mirrors to look all over the mouth, including around and under the tongue.  They also feel with their fingertips for any lumps. Recently, some dentists and primary care doctors have begun to use new tools that are intended to help identify mouth cancer. Many types of these screening aids are available, but they typically use one of the following techniques:

• Autofluorescence: Examination using a blue light that may make potentially cancerous tissue glow (fluoresce)
• Tissue reflectance: Examination using a blue-white LED light after rinsing the mouth with a mild vinegar-like solution that makes to enhance lesion visibility
• Cell tests: Microscopic examination of cells taken from a sore or growth that is of concern
• Salivary tests: Tests for DNA or other markers possibly suggesting cancer done on samples obtained after a patient swishes water in the mouth and spits

The review article in the Journal of the American Dental Association was written by a panel of experts in oral cancer. They focused on evaluating these new testing aids.

The experts reviewed a large number of published studies to determine the accuracy of these testing aids and to evaluate the risks and benefits of using them to screen people for mouth cancer. The possible benefits of screening tests include diagnosing cancer earlier or giving people peace of mind that they did not have cancer. Possible risks include failing to diagnose a cancer and also possibly identifying as cancer a growth that is not cancerous. If a growth is wrongly identified as cancer, people will have unnecessary worry and also have unnecessary additional testing.

What did the experts decide?

The experts determined that there is not sufficient evidence to recommend use of these testing aids. In fact, the salivary tests were imprecise enough that the experts recommended against their use except as part of research studies.

They considered three different scenarios dentists might find after a traditional exam of looking and feeling:

• A growth that is very suspicious for cancer
• A growth that doesn’t seem much like cancer
• No growths in the mouth

The panel recommended that people with visible sores or growths that appear to be cancerous or raise concern should be sent to a specialist to have a biopsy. They shouldn’t take even the small chance that the screening test might be falsely negative. On the other hand, people with no sores or growths visible or felt during a standard examination should have no screening tests because the risk that a cancer was present was low enough that the tests would be likely to find things that weren’t cancer. Finally, people with visible spots or growths that do not seem much like cancer should just be re-examined regularly by their dentists and a biopsy should be done if the spots grow or do not go away after a period of time.

Current recommendations

Until new technologies improve the effectiveness of early detection tests for oral cancers, thorough examination of the mouth combined with a comprehensive review of the person’s risk factors for oral cancers (such as tobacco use, heavy alcohol consumption, previous respiratory or upper digestive tract cancer, increasing age, and some inherited diseases) continues to be most reliable way to screen patients for cancers of the mouth.