You may think you’ve heard all about sexually transmitted diseases, but now a new one poses a threat to your sexual health and wellbeing, albeit looking a lot like one of the old ones. According to wellness writer Charles Bankhead, ‘Once the scourge of older patients with a history of smoking and heavy alcohol use, head and neck cancer has evolved into a disease that strikes people – mostly men – in the prime of life. The driving force behind the molecular transformation is the same one that has received so much attention for causing cervical cancer in women: human papillomavirus (HPV). What’s more, the same oncologic strains drive both types of cancer.’
Bankhead notes, ‘About 37,000 new cases of head and neck cancer are diagnosed each year. HPV infection accounts for about two thirds of the total, according to the CDC. The “classic” tobacco- and alcohol-related head and neck cancer tended to be oral-cavity malignancies. In HPV-positive majority, oropharyngeal cancer predominates. Many people who were unaware of the role HPV plays in head and neck cancer probably learned about it last summer when actor Michael Douglas announced publicly that his head and neck cancer was caused by HPV infection, which he attributed to oral sex…Douglas’s announcement drew public attention to what authorities in the field have known for years: Head and neck cancer is essentially an STD, or at least a manifestation of one.’
Anil Chaturvedi, PhD, of the National Cancer Institute, points out that the incidence of oral-cavity cancer remained stable from 1973 to 1984, and then began a decline that continues today, reflecting trends in tobacco and alcohol use. The incidence of oropharyngeal cancer, on the other hand, increased gradually until about 2000. The proportion of HPV-positive oropharyngeal tumours has increased from 16% in the late 1980s to 72% since the turn of the century. Chaturvedi explains, ‘The increase in oropharynx cancer has come exclusively from an increase in HPV-positive cancers, which increased by 225. In parallel over the same period, the incidence of HPV-negative oropharynx cancer has declined by about 50%.’
Bankhead points out, ‘The emergence of HPV-positive oropharyngeal cancer has been driven almost entirely by oral HPV infection, which has become incredibly common. Data from the National Health and Nutrition Evaluation Survey showed a 7% prevalence of oral HPV infection among US adults – one in 14. Oral HPV infection occurs two to five times more often in men than women…Current prevalence estimates are 10.1% among men and 3.6% among women. Infection rates in both sexes are driven predominantly by sexual activity, accounting for more than 80% of cases in women and almost 90% in men. The risk of infection increases with the number of sex partners in both men and women and with smoking, rising with the number of cigarettes smoked.’
Amber D’Souza, PhD, of Johns Hopkins School of Public Health, admits, ‘It’s been hard to say which [sexual] behaviours transmit the infection. We know that it can be transmitted by oral sex. We know that performing oral sex on a woman increases the risk of acquiring HPV infection and that performing oral sex on a woman appears to have a higher risk of infection than performing oral sex on a man…It is a sexually transmitted infection. It is not casually transmitted.’ She adds that three-quarters of infected individuals clear the infection within two years. ‘Then there’s this subgroup of people who have persistent infection,’ she says. ‘We still think most of them will not develop HPV-positive oropharyngeal cancer.’ As many as 85% of patients survive without recurrence or with effective treatment at recurrence. However, that leaves 15% who don’t do so well, and the reasons remain a mystery.