Here's How Oral Sex Causes Cancer

Human papilloma virus HPVPapilloma Virus (HPV) Electron micrograph of a negatively stained human papilloma virus (HBV) which occurs in human warts.

HPV is a sexually transmitted virus that’s been in the news a lot over the past few years, with the development and controversy over a vaccine to protect against contracting it.

And now, Michael Douglas has said that his throat cancer was caused by HPV transmitted through oral sex — a problem that’s been growing and growing over the past few decades.

HPV doesn’t cause all oral cancers, but it is becoming a bigger and bigger cause of them. In the 1980s about 16% of all oral cancers were HPV-related, but in the early 2000s, that number was 72%, according to researchers at the National Institutes Of Health.

Another study, published in February of 2012 in the Journal of the American Medical Association, found that about 7% of men and women between 14 and 69 years old had detectable oral HPV infections, 1% of these infections were with the oral cancer-causing HPV16 strain.

The CDC notes that every year strains of HPV cause 360,000 cases of genital warts, 12,000 cervical cancers, 2,100 vulvar cancers, 500 vaginal cancers, 600 penile cancers, 2,800 anal cancers in women, 1,500 anal cancers in men, 1,700 oropharyngeal cancers in women, and 6,700 oropharyngeal cancers in men.

HPV, known to scientists as the human papilloma viruses, are a group of more than 100 viruses transmitted through contact. Some of the HPV strains cause warts on other parts of the body, but about 40 strains infect the genital areas.

It can be passed with just skin-to-skin contact — even with a condom, though condoms can lower the risk of catching the virus. The best way to avoid HPV is to get vaccinated against it. Widespread vaccination against HPV would significantly reduce these cancers, since the shot protects against the cancer-causing strains HPV16 and HPV18, among others.

These can be passed to the mouth and throat and infect cells there through oral sex, and even open-mouthed kissing, according to a 2009 study in the Journal Of Infectious Diseases. These infected cells sometimes form into tumors.

It takes decades for HPV infections to manifest into cancers. Other factors may increase the probably of an HPV-infected throat becoming cancerous. Smoking and drinking make these cancers more likely, according to the CDC

The increased rate of HPV throat cancers may be because of increasing oral sex or higher rates of the virus in the population, as people are more sexually liberal and having more sexual partners.

Most sexually active people will be exposed to at least one strain of HPV during their life. Most of the time, our immune systems can clear the virus without it causing symptoms. If the virus isn’t cleared, it can linger and, if it’s one of the cancer-causing strains, it could cause cancer.

Gardasil is the vaccine that protects against several of the worst strains of the virus. Its introduction has been controversial because doctors recommend that it be given to girls and boys as young as 11 years old, to protect them against the sexually transmitted disease before they start having sex. 

The problem? Parents don’t want to think about their 11-year-old children having sex and getting STDs. Some parents think that getting their kid the shot will even encourage them to have sex, since they will be protected from HPV. Others are scared that the vaccine could have side effects.

Only about 1% of boys are being fully vaccinated, and 35% of girls, according to the CDC. If more people get vaccinated against the cancer-causing HPV strains, rates of HPV-induced cancers should drop.

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