Source: www.theprovince.com
Author: Iris Winston, Canwest News Service

Oral cancer brings to mind images of longtime chain smokers and grizzled tobacco chewers. But the risk factors for cancers of the mouth and throat now include sexual activity as well as all forms of tobacco use and alcohol consumption.

“Over the 20 years I have been in practice, I have treated a few rodeo riders and baseball players who use chewing tobacco or snuff, as well as smokers,” says Dr. Joseph Dort, a professor of head and neck surgery at the University of Calgary’s faculty of medicine and president of the Canadian Society of Otolaryngology.

“Classically, people think of oral cancer as something that occurs in smokers and drinkers and usually among people in their 50s, 60s or even older. But, over the last 10 years or so, we have become aware that the human papillomavirus (HPV) — the same virus that is associated with cervical cancer — has now been strongly associated with certain kinds of head and neck cancer, specifically the tonsil and tongue-based cancers, and that they are becoming more prevalent in people who are younger than the usual cohort.”

Dr. Linda Lee, a specialist in oral pathology and oral medicine who is the staff dentist at Toronto’s Princess Margaret Hospital, has seen a similar trend. “Because people are smoking less, we would expect to see a decline in oral cancer,” she says, “but it hasn’t declined and this is probably because of the HPV factor. We have been used to seeing oral cancer in people who smoke, drink and don’t take care of themselves. Now we are seeing some types — in particular, of the tonsils and the base of the tongue — among younger, healthier people who weren’t smoking. There is pretty good evidence that it is caused by the same virus that causes cervical cancer in women.”

The Canadian Cancer Society notes that risk factors for being infected with HPV, which may lead to cervical cancer and is linked to oral cancer, include having multiple sex partners, a partner who has had numerous partners and having a weakened immune system.

Health Canada reports that oral cancer is the 13th most common cancer (of the 23 reported cancers). In 2009, the number of new cases and deaths due to oral cancer was almost three times higher than that of cervical cancer and almost double the rate of liver cancer. Health Canada also estimated that of the 3,400 new cases of oral cancer through 2009, 1,150 people — more male than female — would die from oral cancer.

Canadian Dental Association vice-president Dr. Rob MacGregor, who practises in Nova Scotia, points out that “currently, the survival rate for oral cancer is only 63 per cent for five years, which is not very good. As with any cancer, early detection and diagnosis is key, so it’s important for patients to see an oral health care professional regularly, particularly if they are in the high-risk groups — those who use tobacco, abuse alcohol or have been exposed to HPV.”

“The good news about the type of oral cancer associated with HPV is that it has a much better prognosis,” says Lee. “People survive it much better and do much better as far as cure rates go. Although it hasn’t been shown yet, I think that the vaccine for HPV, now given for cervical cancer to girls, is going to make a big difference. As this type of oral cancer (linked to HPV) occurs more in males, it might be a reason for males as well as females to be vaccinated.”

Tobacco, explains Lee, has been described as an initiator of cancer, and “alcohol is more of a promoter, so the two of them together are worse than either one taken separately.”

She also notes, “mouth cancer in general comprises about 2.5 per cent of all cancers in Canada, so it is quite low here.” By comparison, she adds, “in India, where they have different habits, such as chewing betel nuts, it can be up to 50 per cent of all cancers.”

Additional factors leading to some types of oral cancer include the use of marijuana and chronic inflammation of an area of the mouth.

“I can think of a number of people from my own practice where I have seen a broken, worn tooth chronically digging into the tongue eventually causing inflammation and irritation that can sometimes turn into cancer,” says Dort. “But this is just anecdotal experience. I am not aware of any study that says sharp teeth cause tongue cancer. The association of oral cancer with HPV is much more solid.”