One of the first reports that suggest the involvement of HPV in head and neck cancer dates back nearly two decades ago and it was “greeted with incredulity.” Although there have been more scientific papers reporting that head and neck cancer, especially around the oral cavity is linked to HPV, there has been little information available to the public mainly due to the sensitivity of the issue. This is because the HPV-head and neck cancer connection would surely touch on the topic of oral sex.1-4
HPV infection is one of the most common sexually transmitted diseases in the world. It is estimated that 550,000 new infections occur each year in Canada, about 220,000 in the UK and around 6 million in the United States. At least 50% of the sexually active population get HPV at some stage.
There was a time when the disease was simply called HPV. Nowadays, distinction has to be made between genital HPV and HPV infecting other parts of the body. Genital HPV is caused by more than 40 HP virus types. The most prevalent are types 6, 11, 16, and 18. The most common sign of HPV is the development of warts in the genital areas. Ninety percent of HPV infections clear naturally within a couple of years. The remaining 10% can cause cancer involving the sexual organs and the head and neck.5-7
Worldwide, head and neck cancer is the 6th most common malignancy.
Due to smoking bans and stricter environmental guidelines in the workplace, the overall incidence of head and neck cancers is going down. Most of these develop in the mucosal surfaces in the head area such as the mouth, throat, tonsils, base of the tongue and nostrils and are usually classified as squamous cell carcinoma.8-10
Annually there are over 400.000 new cases diagnosed each year with about two thirds occurring in developing countries. 100,000 new cases occur in Europe, 30,000 in the U.S. and in Canada about 4300. In the U.S. it accounts for 3 to 5% of all cancer cases.11-13
The incidence of oropharyngeal cancer is higher in males than in females with ratios ranging from 2:1 to 5:1. Exceptions are the Philippines and Vietnam where incidence is higher among women. For tonsillar cancer the U.S. Surveillance Epidemiology and End Results (SEER) reported the following rates per 100,000 person-years.14-16
Several environmental factors have been linked to head and neck cancers.
So, why is HPV related Head and Neck cancer so newsworthy?
While everyone by now knows the relationship between HPV and cervical cancer, most of the world is unaware of the increasing incidence of HPV related head and neck cancer. 60 to 70% of all tonsil cancers in the U.S. are linked to HPV whereas other studies report that 45 to 95% of oropharyngeal tumours are HPV-positive. In Central and Latin America, the International Agency for Research on Cancer (IARC) tested for HPV 16 in the following cancers and reported the positive cases:19-21
In Australia, data from 2000 to 2005 reported 219 cases of tonsil cancer, 159 cases of tumors at the base of the tongue, and 110 cases in other oropharyngeal site, with the trend of increasing.22
HPV related head and neck cancer represents “a distinct subset of head and neck squamous cell carcinoma, independent of the traditional risk factors and with different clinical presentation and outcome."HPV related cancers are usually located in tonsils (tonsillar cancer) or back of the throat or at the base of the tongue.
HPV-positive oral carcinomas have a different pathology than non-HPV oral cancers. “HPV-positive tumours are usually poorly differentiated and nonkeratinizing and have a basaloid appearance in contrast to the HPV-negative that is more moderately differentiated and keratinizing.” 70% of non-typical tumours contain HPV DNA, usually the E7 gene of HPV 16 subtype indicating that this subset of carcinomas are the so-called HPV-positive oral tumours. HPV antibodies may also be detected in individuals with HPV-positive tumours.23
So, who is getting HPV related head and neck cancer?
Generally it’s the healthy and well-off segment of the population - in other words, people who are not your typical chain smoking alcoholics or junkies. A study by Johns Hopkins scientists showed that patients with HPV-positive tumors are:
Not surprisingly, this topic has become quite popular thruout the general media.
Although not well-publicized until recently, the risks for developing HPV-positive head and neck cancer is closely linked to sexual behaviour and practices such as having multiple sexual partners and oral sex. This may be attributed to the widespread practice of oral sex among the younger generation, which can be traced back to the early 70’s. Of interest marijuana use has also be studied as a risk factor, but so far its role remains unclear.26-29
One of the world’s leading pioneers on exposing the relationship of sexual practices and head and neck cancer, Maura Gillison MD, PhD, has published extensively on this subject, as well as others. “Sexual behaviours associated with HPV-positive cancers included increasing numbers of lifetime vaginal or oral sex partners, participating in casual sex at least once, infrequent use of barriers during vaginal or oral sex, and having had at least one sexually transmitted disease. People… who reported having a history of six or more oral sex partners were three times as likely to develop the cancer as people who reported that they had never had oral sex. Six or more oral sex partners increased risk for throat cancer by eightfold.'
Dr. Greg Hartig, professor of otolaryngology and head and neck surgery at the University of Wisconsin School of Medicine and Public Health in Madison summarizes it well: “The general consensus on the street is that because people's (sexual) practices have changed over time, we're seeing an increase in these cancers. I don't know why they're having more oral sex (but) the concept of having oral sex is something that seems less obscure to you than it did to your parents or grandparents".30
What about the current HPV vaccines?
Gardasil is quadrivalent and targets HPV types 6, 11, 16, 18 and Cervarix is bivalent and targets HPV 16 and 18. These vaccines were designed to prevent HPV infection that can lead to cervical cancer in women.31
Recently, Gardasil has also been approved for the prevention of anal cancer in men. However, there is currently no data to show whether these vaccines are also effective against HPV-positive oral tumours but studies are ongoing.
The Bottom Line
The silver lining behind the cloud is that the prognosis for most HPV-positive oral tumors is generally better than those that are HPV-negative. Clinical outcomes and survival are usually positive regardless of treatment strategies. This may be partly due to the fact that patients with HPV-positive tumors tend to be young and in good health. However, recently, a subgroup of highly aggressive HPV-positive oropharyngeal cancers has also been identified that needs to be studied closely.32
The take home message is…Modifying sexual behaviour is the key in preventing HPV and HPV-related cancers. Oral sex seems to be the main mode of transmission of oral HPV that leads to cancer although transmission by mouth to mouth contact through French kissing cannot be ruled out.
Staying in a strictly monogamous relationship and avoiding risky sexual behavior can probably prevent HPV infection and transmission. However, refraining from oral sex will probably significantly lower your risk.
Published April 29, 2011, updated July 25, 2012
Photo By: Com Salud