Recent research on oral cancer made headlines — and raised concerns — when scientists reported that poor dental hygiene and excessive use of mouthwash containing alcohol could increase the risk of the disease.
Each year, some 40,000 Americans — and upward of 640,000 people worldwide — are diagnosed with oral cancer, which can occur in the tongue, the floor of the mouth, the gum and the cheek. Deaths from oral cancer in the U.S. last year were estimated at 7,890.
The findings, published in Oral Oncology, came from work conducted by the Leibniz Institute for Prevention Research and Epidemiology with help from Glasgow University's Dental School.
Do the results mean you should cut back on mouthwash swilling? To learn more, we spoke with Bhuvanesh Singh, a head and neck cancer surgeon at Memorial Sloan Kettering Cancer Center. Here are highlights from our conversation, edited for length and clarity.
What are the known risk factors for oral cancer?
Tobacco and alcohol. Independently they have a carcinogenic effect. The effect when used in combination is multiplicative rather than additive. Smokers and drinkers get a big jump in risk for oral cancer.
The other major factor is betel nut. The most common cancer in young men in countries like India and Pakistan is oral cancer, attributed to chewing betel nut or paan [a preparation that includes betel nuts and betel nut leaves].
Should poor oral hygiene and mouthwash be added to the cancer risk list?
Once you get beyond those three factors, the other ones are more difficult to link causally. Poor oral hygiene and use of mouthwash certainly may be contributing, but the extent is difficult to define.
People who tend to be smokers or drinkers are the ones who tend not to take care of hygiene in general. That's not a universal statement, but in general. Whether poor oral hygiene caused the oral cancer is a little more difficult to define. Studies say the bacterial population in the oral cavity may be contributing to development of oral cancers, but these aren't large enough to establish a definitive association. I would call this a soft factor. The same goes for mouthwash use. There is a potential association there. I tell my oral cancer patients to not use alcohol-containing mouthwashes — the alcohol is probably the main carcinogen to worry about. But I don't tell them not to use mouthwash at all. There is no known harm to non-alcohol-containing mouthwashes.
Is there any advantage to a mouthwash with alcohol compared with one without it?
I don't believe so.
Getting back to betel nut, do we know why it's carcinogenic?
We don't know the exact carcinogenic agent. There's still debate about the exact carcinogenic agents in tobacco and alcohol as well. Tobacco has about 400 known carcinogens. It's probably a combined effect.
Has betel nut chewing crossed over into American immigrant communities?
Betel nut chewing requires a lot of spitting. The social acceptance [of spitting] in the United States is not the same as in other countries. That may be a limiting factor.
How difficult is it to treat oral cancer?
The earlier it presents, the easier it is to treat. More advanced tumors are difficult to treat, but we certainly still have the ability to cure them. So the key for oral cancer is early detection. A good dentist should perform an oral cancer screen.
And that's done by feel?
Oral cancer is a surface cancer. Early [tumors] often won't show up on any imaging study and are best identified by clinical exam.