In Nature this week Megan Scudellari wrote a fascinating/disconcerting history of the medical community's realization that human papillomavirus (HPV) is causing many thousands of cancers well outside of the cervix:
Until the late 1990s, most cases of cancer in the back of the throat (the oropharynx) could be blamed on alcohol and tobacco use: the majority of [molecular oncologist James] Rocco's patients were men around 50 years old, who had been smoking and drinking for 30 years. But then 40-year-old marathon runners and people in otherwise good health began to trickle—then stream—into his office.
In 2005, Ohio State professor Dr. Maura Gillison's research found:
... people with head and neck cancer were 15 times more likely to be infected with HPV in their mouths or throats than those without. The association backed up some of Gillison's earlier work, which showed how HPV DNA integrates itself into the nuclei of throat cells and produces cancer-causing proteins. Gillison leapt from her chair and began jumping up and down. “The association was so incredibly strong, it made me realize this was absolutely irrefutable evidence,” she said.
Since then, she and a network of other researchers have amassed a mountain of evidence that HPV causes a large proportion of head and neck cancers, and that these HPV-positive cancers are on the rise. The finding has been “a paradigm-shifting realization in the field,” said Robert Ferris, chief of the division of head and neck surgery at the University of Pittsburgh Cancer Institute in Pennsylvania.
The medical community is struggling to come to grips with the implications. ... If HPV can get into the mucous membranes of the mouth and throat, where does it stop? ... “Our clinics are flooded” with head and neck cancers triggered by HPV, she says, vexation clear in her voice. “But though I talk about it constantly in public settings and the lay press, it amazes me that it's often as if no one has heard of it.”
Some people have heard of it I hope, if not because of Michael Douglas going very public with his own diagnosis of HPV-related-oropharyngeal-cancer in June, then because this is something every parent learns before vaccinating their kid against HPV. Most American kids still are not vaccinated, though.
This story does make me wonder not just what other cancers might involve HPV, but how many other infectious pathogens might be, unknown to us, contributing to cancers — infections that we could possibly be preventing with vaccines or treating with antibiotics. Right now we understand about 6 percent of cancer cases in industrialized countries to be the result of some kind of infection. In the developing world it's closer to 25 percent.