Throat cancer linked to HPV: Western world's fastest emerging cancer

Dr. Donald Brown holds the human papillomavirus vaccine Gardasil in his hand at his Chicago office Monday, Aug. 28, 2006.(AP / Charles Rex Arbogast)

Actor Michael Douglas' comments about throat cancer and oral sex have thrown a spotlight on a form of cancer that’s a growing cause for concern.

Here’s what we know about HPV and oral cancer:

HPV can indeed cause throat cancer

HPV might be best known to Canadians as the virus that can lead to cervical cancer, but there are more than 100 strains of the virus, some of which can infect the genital or anal areas and can be sexually transmitted to the oral and throat areas.

Certain HPV strains can cause genital warts, others cervical cancer, others -- particularly HPV-16 – can cause cancer of the oropharynx, meaning the back of the throat, the base of the tongue and tonsils.

The strains linked to cancer of the throat and pharynx typically infect the female genital area and are spread through cunnilingus.

Rates of HPV-related oral cancers are on the rise

Dr. Eduardo Franco a cancer epidemiologist at McGill University in Montreal says that throat cancer due to smoking and drinking is on the decline, in large part because smoking rates are declining, while cases of throat cancer related to HPV are on the rise.

Dr. Brian O’Sullivan, a head and neck cancer specialist at Princess Margaret Hospital in Toronto, says throat cancer linked to HPV is the Western world’s fastest growing cancer.

It’s not clear what proportion of current oropharyngeal cancer can be linked to HPV, but Franco estimates 35 to 40 per cent of cases diagnosed in Canada can be blamed on the virus.

In the U.S., the U.S. Centers for Disease Control and Prevention (CDC) says 60 per cent of such cancers are linked to HPV, though many of those are also related to tobacco and alcohol.

In women, rates of HPV-related throat cancers have remained stable. But in men, the increase in HPV-related throat cancer is likely due to the acceptance over the last few decades of oral sex, particularly among young people, who assume it is less dangerous than intercourse.

Most men diagnosed with HPV-related cancer are in the 55 to 64 age group. This might be a reflection of the fact that HPV-related cancers typically take many years to develop.

HPV is the most common sexually-transmitted infection in Canada

It is estimated that more than 75 per cent of sexually active Canadian men and women will have a sexually transmitted HPV infection at some point in their lives. Some put that number even higher.

Most HPV infections occur without any symptoms and go away without treatment. But some strains persist and can cause cells in the genital, anal and oral area to become cancerous.

There is no cure for HPV infection, but the warts, lesions and cancerous changes caused by the virus can be treated.

Use of dental dams during oral sex can also reduce the risk of HPV transmission. There are also two vaccines available in Canada, Gardasil and Cervarix, both of which help prevent HPV-16, the strain that causes the most cases of oropharyngeal cancer.

Dr. O’Sullivan says the key to getting HPV infection rates down is through vaccination and says that boys should become a target group for public education and vaccination. Public HPV vaccination programs in Canada and the U.S. are mainly aimed at girls, though Prince Edward Island recently announced it will be opening up its program to both genders.

“We need to face the problem, and this is a real problem and a preventable problem in the long term,” O’Sullivan said.

The Society of Obstetricians and Gynecologists of Canada also says provincial and territorial HPV vaccination programs should be expanded to cover boys.

Oral and throat cancer linked to HPV can be successfully treated

Upper throat cancers are typically treated with chemotherapy, but doctors are finding that patients with HPV-positive oropharyngeal tumours tend to have a better prognosis.

Researchers are now looking at whether these patients can be treated with less intensive treatments.

Though the warts, lesions and cancerous changes caused by HPV can be treated, there is no cure for HPV infection itself.

Symptoms of oral and pharyngeal cancer include: