Friday March 26 2010
Human papilloma virus may be linked to rise in mouth cancer
The Daily Telegraph reported that a “rise in mouth cancer may be due to sexually transmitted infection”. The newspaper said that there has been a 50% increase in the number of mouth cancers in the last 20 years, and the increase appears to be in those cases related to the human papilloma virus (HPV).
The story is based on an editorial in the British Medical Journal by cancer specialists, which highlighted an increase in the numbers of a specific type of throat cancer in the UK. The specialists also discussed studies from other countries that show an increase in the proportion of HPV-related throat cancers.
The editorial reported on a very small number of studies, but it shows that there may be a need to investigate the incidence of HPV-related throat cancers in the UK, to track these cases and to see if HPV-related cancers should be treated differently to non-HPV-related throat cancers. There is insufficient evidence at the moment to suggest that the HPV vaccination, currently available for teenage girls, should also be given to boys.
Where did the story come from?
This editorial was written by Hisham Mehanna, director of the Institute of Head and Neck Studies and Education at University Hospital, Coventry, and colleagues at the University of Liverpool, Université Catholique de Louvain and the University of Texas.
The editorial was commissioned and published by the British Medical Journal and was not externally peer reviewed.
What was the editorial about?
This editorial was written by cancer specialists to highlight the increase in throat cancers in the UK, an increasing proportion of which are thought to be related to HPV.
The researchers looked at a particular type of throat cancer, called oropharyngeal squamous cell carcinoma, in men. They say that, between 1989 and 2006, there was an increase from seven cases per 100,000 men to 11 cases per 100,000. The authors discussed the implications of this rise for both prognosis and policy decisions, and also looked at the proportion of this type of throat cancer that may be associated with HPV.
What evidence did the editorial put forward?
The authors suggest that the increase in numbers of oropharyngeal squamous cell carcinoma could be accounted for by a rise in HPV-related oropharyngeal carcinoma.
They cite a study from Stockholm in Sweden, which looked at how many biopsies from this type of cancer were positive for HPV. The results suggest that 23.3% of biopsies were positive for HPV in the 1970s, compared with 93% between 2006 and 2007. They say that another study in America found that 60-80% of recent biopsies from this type of cancer were HPV positive, compared with 40% in the previous decade.
Smoking and alcohol consumption increase the risk of throat cancer. The authors cite research which suggests that the prognosis for HPV-positive throat cancers is better than for non-HPV-related cancers. This research suggests that advanced HPV-related throat cancers are associated with a two-year survival rate of 87.5-95%, compared with 62-67% for advanced non-HPV-related cancers.
The authors suggest that oral sex may be a means by which HPV is passed on and that this could be a reason for the increase in the incidence of HPV-related oropharyngeal cancers in the UK. They discuss an analysis of eight studies on the risk of various types of head and neck cancers in men and women in various countries (excluding the UK) with increasing numbers of sexual partners. The analysis had a total sample of 5,642 people with head or neck cancer and 6,069 controls. There was a borderline significant increase in the risk of developing oropharyngeal cancer for people who had six or more lifetime sexual partners (odds ratio [OR] 1.25, 95% confidence interval [CI] 1.01 to 1.54), four or more oral sex partners (OR 3.36, 95% CI 1.32 to 8.53) and an earlier age of first sexual intercourse (OR 2.36, 95% CI 1.37 to 5.05).
The authors did not report data on whether individuals’ sexual practices have changed from 1989 to the present day, or whether the prevalence of HPV viruses (particularly HPV16, which has been linked to throat cancer) within the population has changed in this period.
What policy and practice implications do the authors suggest?
The researchers say that studies looking at an HPV vaccination scheme for boys, similar to that offered to teenage girls, showed that it may not be cost-effective owing to the low numbers of oropharyngeal cancer. However, they say that in time, an increase of this type of cancer may affect the cost-effectiveness of such a vaccination scheme. They say that the female-only HPV vaccination programmes may affect the incidence of HPV-related oropharyngeal cancers.
The researchers also say that patients with HPV-related head and neck cancers currently receive the same treatments as patients with non-HPV-related cancers. They say that clinicians should not change their treatment policies, but may wish to offer patients with oropharyngeal cancer the opportunity to enrol in clinical trials, which are currently being planned to look at different treatment options for HPV-related cancers.
The authors have highlighted the increasing incidence of oropharyngeal cancers in men in the UK. They have associated this with an increase in the proportion of HPV-related cancers based on studies in Sweden and the US.
Further research is needed to assess whether the increase in oropharyngeal cancers in British men reflects an increase in HPV-related or non-HPV-related cancers. As HPV-related and non-HPV-related throat cancers have a different prognosis for survival, further research may look at whether different treatments can have different effects on these two throat cancer subtypes.
There is insufficient evidence at present to suggest that the HPV vaccination currently given to teenage girls should also be given to boys.