In 2013 actor Michael Douglas said in an interview that the tongue cancer he had suffered three years earlier had been caused by oral sex.
It was known that HPV caused cervical cancer but it was not until a few years ago that it was discovered that it also caused a subtype of head and neck cancer, which is how they named those affecting the oral cavity, the pharynx and the larynx. Last year, Nature magazine published an article «HPV: Sex, Cancer and Virus», which considered Maura Gillison’s research, one of the researchers who has contributed further evidence that HPV is the cause of some types of tumours, mainly located in the oropharynx (back of the oral cavity).
More cancers caused by HPV
Alfonso Berrocal, head of oncology at the General Hospital of Valencia and board member of the Spanish Head and Neck Cancer Cooperative Group, explains that, indeed, «there has been a change in the epidemiology of head and neck cancer. It is increasing in a different population, who are the patients who have been infected with human papillomavirus. In fact, it is possibly a clinically and molecularly different cancer to the one we are used to see so far, in the sense that it tends to affect younger people, between 35 and 40 years of age, and in more specific locations such as the oropharynx».
HPV infection has no equal distribution across geographic territories. «In the United States and Northern Europe there is an increase in oropharyngeal tumours associated with HPV. It is estimated that about 60% of cases, 80% for the Swedish, are associated with it» Alfonso Berrocal claims. He goes on explaining that in Spain and in Southern Europe in general, the incidence of HPV infection is lower, «the HPV incidence rate in this type of neoplasms is 15-20%. This can possibly be attributed to the fact that changes in sexual behaviour occurred a little bit later».
It is not so much about sex, but about the number of partners
Have we changed our sexual habits that much or is it that modern tumour analysis techniques allow us to gain insight into its causes? «It is possibly a combination of factors. Earlier we did not perform HPV serologies, but now we do. Moreover, cigarette consumption is decreasing so consequently we find an increasing proportion of other cases that have nothing to do with smoking. And, obviously, there has been indeed a change in our sexual habits. The available studies claim the importance of a significant number of partners. The last report I have checked, the Swedish one, establishes changes in incidence between 1 and 6 partners, 6-25 and over 25. The highest risk was above 25 partners and that was not so common before, but now it is. What it really has to do with is the increasing number of partners and the fluid interchange. And in those terms, habit changes have been important» Dr. Berrocal explains.
We have to bear in mind that not all HPV infections cause cancer. In fact, most sexually active people end up being exposed to the virus at some stage in their lives but only some are oncogenic HPV serotypes: «In cervix cancer oncogenes 16 and 18 are the ones. In head and neck cancer, almost 95% of cases are associated with oncogene 16. But being infected with serotype 16 does not necessarily mean that you will eventually develop cancer. Only some people will develop neoplasia and there may be other additional factors: some form of immunosuppression or associated comorbidity that favours the progression of the disease» Alfonso Berrocal claims.
Higher incidence in men
It is also attributed to habits the fact that head and neck cancers affect more men than women: one woman every five men in the case of cancers produced by etiologic agents like alcohol and tobacco, and one every three men in those caused by HPV.
Similarly, the mechanisms by which carcinogenesis is activated are different when etiology is viral and when it is caused by carcinogens like tobacco. utations in tumour cells are different and that makes tumours behave differently. We have seen that the ones caused by HPV have higher cure rates and so now we study whether less aggressive treatments in these patients could achieve the same cure rates or not.
«It was known that HPV caused cervical cancer but it was not until a few years ago that it was discovered that it also caused a subtype of head and neck cancer»
«Most sexually active people end up being exposed to the virus at some stage in their lives»
An unknown cancer
Head and neck cancer is the sixth most common cancer type in Europe. According to the European Head and Neck Society (EHNS), over 150,000 people were diagnosed with these cancers in 2012. 60% of these, more than half, were at an advanced stage of the disease, which complicates the prognosis and requires a more aggressive treatment. When the patient is at an early stage, cure rates reach 90%. This is why the EHNS launched the «Make Sense Campaign», two years ago, to raise awareness regarding this type of cancers.
While some celebrities like Michael Douglas, have not hidden their disease, head and neck cancer is still widely unknown. «It is a type of cancer associated with activities such as excessive alcohol and cigarette consumption and now also with sex, so these tumours, I believe, are the kind people tend to hide. The father of the former king of Spain had a head and neck cancer [larynx] and that did not contribute to a wider dissemination of the disease. In fact, experts gather that it is a disease which is still relatively unknown and that makes people go the doctor when it is too late” Alfonso Berrocal claims.
Similarly Marta Camps, dentist and doctorate under the direction of José Vicente Bagan, head of the department of stomatology at the General Hospital of Valencia, claims: «I saw a lot of hospital dentistry and this is why I have so much training in diseases … Now it has been almost twenty years of me seeing patients at the clinic and there are still some that say, ‘oh, is there such thing as oral cancer? ‘ People know very little about it».
Many campaigns try to diffuse the symptoms of this cancer in order to be able to make an early diagnosis of the disease. Hoarseness, sore throat, discomfort when swallowing, mouth ulcers, white or red patches on the tongue, a decrease in salivation or a change in mucous membranes, are some of the symptoms that require a visit to the doctor if they persist after three weeks. Also «an injury that is hard to the touch. A hard lump in a mucosa which is soft is suspicious as well» adds Marta Camps who considers that early diagnosis is critical, «you cannot keep the patient mouthwashing for three months to see how it goes». She admits that she has seen more cases than she ever imagined in her professional life: «I thought I would see one, maybe two, but lately I have seen many more. In July, two in the same morning. I spent the whole summer thinking about it and in September, after my holidays, I saw two more cases». However, Marta Camps emphasizes a positive aspect: «Oral cancer can be cured if diagnosed».
The Importance of Prevention
For now, head and neck cancers do not have any screening system. Currently there is research on some proteins associated with the infection that aims at detecting them in saliva or in the oral cavity but it is still undergoing experimentation.The best prevention is still eliminating major risk factors: tobacco and alcohol. What is more, «cigarette consumption may potentiate HPV effects, so reducing alcohol and tobacco is always positive» according to Alfonso Berrocal. A good hygiene of the oral cavity is also important as well as acquiring the habit of visiting the dentist once a year and self-examining your mouth in front of the mirror.
«While some celebrities like Michael Douglas, have not hidden their disease,·head and neck cancer is still widely unknown»
|Lucía Sapiña. The Two Cultures Observatory. Mètode.
© Mètode 2014.