Increasing evidence suggests that HPV infection of the mouth and throat, presumably acquired through oral-genital contact with an infected partner, can lead to squamous cell cancers of the tongue and tonsils.You know what HPV is, right? Human Papilloma Virus. The same virus that can cause cervical cancer in women and anal cancers in both men and women.
Scientists have been suspecting for years that this virus might be responsible for squamous cell cancers of the oral cavity. Turns out that it is, though it may be a more recent phenomenon related to the increasingly widespread nature of HPV infection.
What is the Evidence?
1. The incidence of certain oral cancers is rising
Doctors and dentists are seeing increasing numbers of tonsillar and tongue cancers in young men and women, even as rates of other oral cancers and the use of tobacco, a factor typically associated with increased risk of oral cancer, have declined, and rates of oral sex have increased.
Confounding factors may be an increase in binge drinking, another risk factor for oral cancer, and the fact that tonsillectomies are no longer regularly performed. But upwards of one quarter of individuals with oral cancer these days do not have a history of drinking or smoking, suggesting that another risk factor is emerging. That factor appears to be HPV.
2. HPV DNA is found in oral cancer cells
Somewhere between 40 and 75% of tongue and tonsillar cancers contain HPV16 DNA. HPV 16 is the HPV genotype most frequently found in cervical and anal cancers, and is known to be sexually transmitted.
Scientists testing tumor samples from Sweden’s tumor registry in 2007 found that the rate of HPV DNA presence in tonsillar cancers increased from 23% in 1975 to 68% in 2002.
3. The risk for oral cancer increases with number of oral sex partners
Having more than 6 lifetime oral sex partners is associated with a greater than threefold increase in oral cancer risk. (NEJM) This risk appears independent of the risk imparted by smoking and alcohol, which is associated with HPV-negative cancers. Again, this suggests that there are separate pathways to oral cancer, one mediated by HPV and the other via some other factor modified that is by alcohol and nicotine.
What is Your Risk for Getting Oral Cancer?
It’s really, really low. According to the SEER database, the the annual incidence of oral cancer is about 10 per 100,000 annually (6 per 100,000 for women and 16 per 100,000 for men.)
So extrapolating from the research, having had oral sex with more than 6 partners would raise the annual risk of oral cancer in a male to 48 per 100,000.
Of course, that’s just the annual risk. The lifetime risk of getting oral cancer is considerably higher, about 1%, give or take, depending upon how old you live to be.
So, if these numbers hold for HPV related cancers as well, and you have more than 6 oral sex partners, your lifetime risk for oral cancer by age 70 will be about 3 %. Which looks like this –
But, the risk of dying from oral cancer is much, much lower, about 2.5 per 100,000 annually, and ranges from 1.3 per 100,000 in individuals under age 65 to about 12 per 100,000 in those age 65 and older. Since HPV cancers are less aggressive than other oral cancers, I don’t think we can extrapolate historic mortality data, so I won’t. But I would suspect that the risk of dying from an HPV-related oral cancer is even lower than the numbers I just quoted.
(This is rough math, and probably not statistically proper, but it’s the best I can do with the data I have. Others who are better at statistics, please feel free to comment and correct this estimate and I will revise if need be.)
By comparison, the annual incidence of cervical cancer in women is about 7 per 100,000 and the mortality about 2.5 per 100,000. The lifetime risk is about half that of oral cancer in males, due, I suspect, to Pap smear screening in women.
Are There Other Risk Factors?
HPV is only one risk factor for oral cancer, though given the advent of the HPV vaccine, it is sure to be the one that gets the most press.
Smoking, excessive alcohol intake and poor dental care are also very important risk factors, as is a diet low in fruits and vegetables. In one study in Poland, 56% of oral cancers could be attributed to smoking, 31% to excessive drinking, 47% to poor dental hygiene and dental care, and low fruit intake to 12%.
These other risk factors appear to be independent of HPV infection in causing oral cancers, and scientists hypothesize two separate paths to oral cancer, one driven by HPV and the other by these other risk factors. Supporting this idea is the fact that HPV-related oral cancers tend to be less aggressive and have better prognosis than those without HPV. In addition, tobacco and alcohol appear to be synergistic in promoting cancers that are negative for HPV, but not in cancers that test positive for the vurus, again suggesting separate mechanisms for malignant transformation.
What Can You Do Now to Prevent Oral Cancer?
1. Don’t smoke
2. Drink to moderation
3. Brush your teeth and see your dentist regularly.
4. Add fruits and vegetables to your diet.
5. Limit your number of oral sexual partners
Will HPV vaccination be added to that list? I expect it will be. The vaccine prevents HPV 16, the subtype most often found in oral cancers.
Merck, the manufacturer of the vaccine, is conducting clinical trials of their HPV vaccine in young men. I would anticipate a “Tell someone” campaign about oral cancers directed at this population sometime in the near future. Time will tell, and only Merck’s marketing department knows for sure.
In the meantime, be careful out there, okay? Oral sex is a very intimate activity. Why not reserve it for those you love? That would limit your partners quite nicely.
Prevention of so many diseases come down to “don’t smoke, drink in moderation, add fruits and vegetables to your diet, and limit your number of sexual partners”.
I really like your blog.
Thanks, RL! Back at ya’
Sometimes it just seems like there’s no winning. And, in the end, of course, there isn’t. But could I at least go with a smile? A goofy, tired smile?
Very interesting, thanks for info.
bardiac – I know how you feel. There’s nothing fun left, is there?
Oh yes there is – BIKING!
Well, I am not at all surprised. Merck will no doubt go after this, and I find it interesting that they are in a trial with men…I immediately want to know what the difference will be for exposure for gay men vs. straight men. In other words, is giving oral sex to a man have a higher incidence rate then getting from a man, and will the incidence rate for gay men be comparable to the rates for straight women with an equal number of oral sex partners? Should be a great way for conservative America to make HPV a virus of the devil like they did for HIV for that community.
While dying from oral HPV is not likely (thanks for clarifying that!) I can’t help but wonder what the testing and treatment regimens are like. I had my tonsils out at age 35, and it was really painful. I did lose 30 lbs., which was an added plus, but it hurt like hell. Wondering what the treatment options will be like as this becomes a bigger trend.
My next question to Merck will be when will they begin the clinical trials for anal/rectal cancers as well. This will seal the argument for Merck that universal prevention of 6 and 16 will be mandatory for everyone. That will increase their market, huh?. My bet is that they are well on their way to launching the trial. THAT will be an interesting search for willing patients!
I hate viruses.
TBTAM, Um, either I’m doing something wrong, or you have a REALLY special bike! (And I want one! Except I’d probably get distracted and fall. Imagine explaing THAT broken collar bone in the emergency room?)
Bardiac 🙂
Schruggling:
Good questions, all of them, I have no idea of the answers…I can’t figure out why men get more oral cancer than women, since I was under the impression (?Mistaken) that most of the oral sex was coming their way…
Some Australian company is testing a vaccine that covers 90% of cancer causing HPV strains.
http://www.msmagazine.com/news/uswirestory.asp?id=10666
So Merck has about 5 years before this one takes over.
Happy Turkey day!
Thanks for the info! One thing that scares me about this is how many teenagers think oral sex is “really” sex, since it’s not intercourse. A lot of girls in particular think that, since they are still virgins if they have oral rather than genital sex, it’s ok to have oral sex with any guy they go out with. Too bad the pharmaceutical companies can’t put that in a vaccine ad!
Barb
Sorry – that should be is not “really” sex!
Barb
Sorry to jump on this thread so late. I’ve done some research into this, and have the following things to add:
1) I think the risk is actually even lower. Consider this, suppose that half of all Americans eventually get one of the 100 types of HPV strains–this is lower than the CDC’s incidence rates. We know from some sampling and statistics (using Dr. Palefsky’s presentation at UCSF) that half of all HPV infections are the oncogenic types. So, 300 million * 0.5 * 0.5 and you still get a hell of a lot of people with oncogenic HPV. Let’s assume this is optimistic, and say even half of those have oncogenic types. Then, there are roughly 33 million people that have high risk HPV. Okay, the ACS states that roughly 33,000 people every year in the U.S. will be diagnosed with oral cancer. Suppose all 33,000 are caused by high risk HPV. That means that your risk of getting oral cancer if you have high risk HPV is 33,000/33 million * 100% = 0.099% Pretty low, if you ask me.
2) SUpposedly, there will be a new test offered at dentists called the Oral CDX brush test. They basically swab all the areas of your mouth and send in the brush for analysis. Any cells that are picked up that have dysplasia or SCC will alert you to early stage carcinoma. You can look for dental providers that are offering this test. This should be equivalent to a pap smear but for oral.
3) Tonsil removal might not be a good pre-emptive strike akin to a hysterectomy. The reason being is that most times all of the tonsil tissue is not removed, and your tonsils CAN grow back. I’ve known a person who had his tonsils removed, only to have them grow back later.
Chantix is a fairly new drug designed to help people quit smoking. It also has the ability to help people with other addictions such as alcoholism. Chantix works by targeting nicotinic acetylcholine receptors in the brain. http://www.chantixhome.com/