Medical Matters: Proportion of oral cancers being linked to HPV is growing

Hollywood has been driving the health agenda in the media for the past few weeks.

First we had Angelina Jolie drawing attention to the minority of breast cancers caused by the BRCA gene and the choice affected women face in terms of whether to have a prophylactic mastectomy or not. And now Michael Douglas has got in on the act with his claim that human papillomavirus (HPV) infection acquired through oral sex is the reason he developed throat cancer in 2010.

As part of a publicity interview with the Guardian for his latest film, the Liberace biopic Behind the Candlebra, Douglas unexpectedly blamed his oral cancer on his sexual proclivities.

Asked whether he now regretted his years of smoking and drinking, seen as classic causes of the disease, Douglas replied: “No. Because without wanting to get too specific, this particular cancer is caused by HPV, which actually comes about from cunnilingus.”

Douglas continued: “I did worry if the stress caused by my son’s incarceration didn’t help trigger it. But yeah, it’s a sexually transmitted disease that causes cancer.”

Bizarrely he added: "And if you have it, cunnilingus is also the best cure for it."

Suspected cause
A few days later, Douglas's spokesperson disputed the newspaper's headline. The spokesperson said
that the interview simply included discussion of oral sex as a suspected cause of certain oral cancers.

Whatever the sequence of
events, his comments have focused attention on the whole area of oropharyngeal cancer. These are cancers that occur on the tongue, tonsils and the throat.

Head and neck cancers are more common in people who smoke, and especially those who also drink alcohol.

However, about a quarter of
head and neck cancers are diagnosed in people who have never smoked.

Experts believe HPV may play a part in the development of some of these cancers. It seems the virus can lie dormant for many months or even years before causing cell changes that, in some people, may develop into cancer.

What isn’t in doubt is the fact that the proportion of HPV-related oral cancers is growing.

From 16 per cent of all oral cancers in 1984 to 1989, to 72 per cent from 2000 to 2004, HPV-linked oral cancers are on the rise, a report earlier this year from the American Cancer Society and Centers for Disease Control and Prevention found.

And more than 10 per cent of men and 3.6 per cent of women aged 14 to 69 have a current oral HPV infection, according to a study published last year in the Journal of the American Medical Association.

But not everyone with oral HPV infection gets cancer. In about 85 per cent of cases, a person’s immune system gets rid of the infection. And while there are dozens of types of HPV, only a few cause cancer. HPV 16 and HPV 18 cause about 70 per cent of cervical cancers; for oral cancer, the most dangerous subtype is HPV16.

More common in men
Oral HPV infection is more common in men so what about the risk of cancer for a partner of a man with HPV infection?

Research just presented at
the American Society of Clinical
Oncology annual meeting found that 65 per cent of men with HPV-related oral cancer had an active HPV infection.

However, only 5 per cent of female partners of men with oral cancer had an active HPV infection. That suggests these women are not at higher risk for oral cancer. However, about 30 per cent of male partners of men with oral cancer had active HPV infections.

While HPV vaccination prevents cancer of the cervix, there are no studies on its effect on oral cancer.

As to Douglas’s suggestion that cunnilingus might be a cure for oral cancer, one consultant head and neck surgeon was sceptical: “Maybe he thinks that more exposure to the virus will boost his immune system. But medically, that just doesn’t make sense.”

mhouston@irishtimes.com
muirishouston.com