Baseball star Curt Schilling says he has mouth cancer that was caused by chewing tobacco (here). His announcement has generated considerable interest in mouth cancer, its frequency and causes.
What is mouth cancer?
Mouth cancer typically appears in the lining of the mouth; it may start as an ulcer or red area that is discovered in a dental or medical exam. The phrase is often used incorrectly to include cancers of the throat.
Schilling did not disclose the location of his cancer, but he did say that he found a lump in his neck. This indicates that the tumor had spread to a lymph node, a condition that more likely suggests a tumor of the throat, rather than the mouth.
How common is mouth cancer?
It is very rare. Mouth cancer occurs with higher frequency in people who have the risk factors I describe below, but it is possible for someone with no risk factors to develop this disease. As I described previously (here), among 100,000 men age 40+ years, perhaps three or four with no risk factors will develop mouth/throat cancer each year; only one or two of those cases will be mouth cancer.
What causes mouth cancer?
The most common cause of mouth cancer is smoking, which can increase risk 10-fold; smokers who drink alcohol have even higher odds. Alcohol abuse raises the odds about four-fold.
Another recognized risk factor is infection with human papillomavirus (HPV), a sexually transmitted disease discussed previously (here). HPV is considered by some experts to be a significant cause of mouth cancer, but precise estimates of risk elevation are not available.
Schilling attributes his cancer to chewing tobacco. There are numerous studies of the risks related to smokeless tobacco (discussed here). The odds of developing mouth cancer if you use chewing tobacco or moist snuff are about the same as if you didn’t smoke, drink or have HPV. In other words, one or two users out of 100,000 will develop mouth cancer.
Smoking and drinking can produce a cancer anywhere in the mouth, esophagus, voicebox and lungs. HPV is generally linked to cancers of the throat. In contrast, the most common location, by far, for mouth cancer in a smokeless tobacco user is at or very close to where the tobacco is placed, normally between the cheek and gum.
While rare, every case of mouth cancer is unfortunate, and potentially avoidable. Have your dentist or physician perform a thorough head and neck exam every year.