A team at the University of Florida, Baylor College of Medicine and elsewhere found that 11.5 percent of U.S. men were actively infected with oral HPV between 2011 and 2014, and 3 percent of women were. That adds up to 11 million men and 3 million women, the researchers report in the Annals of Internal Medicine.
It’s a sexually transmitted infection and the more sex partners someone had, the bigger their risk. But the study found smoking also increased the danger of a high-risk infection, and, perhaps surprising to some, that men and women alike who smoked marijuana were far more likely to develop a cancer-causing strain of HPV.
“The predicted probability of high-risk oral HPV infection was greatest among black participants, those who smoked more than 20 cigarettes daily, current marijuana users, and those who reported 16 or more lifetime vaginal or oral sex partners,” the researchers wrote.
Most people get over these infections and never even know they had them. HPV doesn’t cause any symptoms at first. But in some people, it stays in the infected tissues and causes DNA damage that, years later, causes a tumor to grow.
HPV is the single biggest cause of cervical cancer and certain types of head and neck cancers called oropharyngeal cancers, according to the Centers for Disease Control and Prevention. Between 2008 and 2012, close to 39,000 people were diagnosed with a cancer caused by HPV every year in the U.S., 59 percent of them women and 41 percent men, the University of Florida team reported.
But while the Pap smear and, more lately, HPV tests have reduced rates of cervical cancer, rates of oral cancer are growing.
“I had zero symptoms, except I found a bump on my neck."
“There are now more of these HPV-related throat cancers in men than there are cervical cancers in women,” said Dr. Erich Sturgis, professor of head and neck surgery at the MD Anderson Cancer Center at the University of Texas.
Frighteningly, the cancers don’t cause any symptoms until they have spread. There is no way to screen people for them — unlike a Pap smear for cervical cancer, there’s not a good test for oral HPV. The only way to prevent infection is the HPV vaccine but once someone’s already infected — and that’s most people over age 26 — the vaccine doesn’t help.
That leaves several generations of Americans vulnerable to these head and neck cancers with no way of knowing if one is silently growing.
“If someone has an oral infection, in theory they can spread it by deep kissing,” he said. Unlike HIV, which is spread by blood and semen, HPV is spread in the fluids of the mucosal membranes — which line the mouth, throat and genital tracts.
“The highest viral loads tend to be in the cervix,” Sturgis said. “Men performing oral sex on women probably tend to get exposed to the highest amount of virus.”
“There are so few specialists in the head and neck region. But there are almost 200,000 dentists across the country."
MD Anderson and other groups are working to encourage HPV vaccination, but they are also trying to fill the gap for people too old to be vaccinated who are at high risk.
“We are working with the American Dental Association. We are working with them both on trying to increase vaccination rates and on reducing smoking rates,” Sturgis said.
“There are so few specialists in the head and neck region. But there are almost 200,000 dentists across the country. And dentists see adolescents. If we could get dentists to at least ask parents whether their kids are vaccinated, just by asking we are going to help improve knowledge about the problem and at least get more of our kids vaccinated.”
The risk hit the headlines 2013 when actor Michael Douglas announced that he was being treated for throat cancer and said he believed it was caused by HPV.
An FDA-approved vaccine — Gardasil — prevents infection with the HPV strains most likely to cause cancer. A new form of Gardasil, approved in 2014, includes nine HPV strains for even more cancer protection.