Does Oral Sex Really Cause Throat Cancer?

Travelling to work early Friday morning, I came across this article in the Metro.

Oral sex virus 'causing throat cancer' as scientists urge male HPV vaccine | Metro.co.uk.

The article is rather heavy on startling, attention-grabbing statements and a bit low on facts. It claims that a virus spread by oral sex might be responsible for the rise in throat cancer in men. The wording used somewhat implies that women are therefore responsible for 'infecting' men with throat cancer. After all, no one is worried about any rise in throat cancer in women.

I couldn't really identify any un-sullied facts in this widely read article, so I set about uncovering the research behind the article.

Where did this story originally come from?

The story is based on an editorial in the British Medical Journal, written by throat cancer specialists. The editorial highlighted an increase in the numbers oropharyngeal squamous cell carcinoma in the UK. This is a cancer of the lining of the mouth and throat.

The specialists also discussed studies from other countries that show an increase in the proportion of human papilloma virus (HPV)-related throat cancers. That means the number of cancers that when analysed, contained particles of HPV.

Although the editorial reported on a very small number of studies, it showed that there may be a need to investigate the incidence of HPV-related throat cancers in the UK, and to see if HPV-related cancers should be treated differently to non-HPV-related throat cancers. This is because more throat cancers these days seem to contain HPV than 30 years ago, and there seems to be a difference in how many people survive treatment of throat cancers that do and do not contain HPV.

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 importantly, it was not externally peer-reviewed. This means that the content has not been read and approved by other experts in the field. This means that their claims are not substantiated by other experts and really only represent the opinion of a number of individuals.

What was the main point of the editorial?

The main focus of the editorial was to highlight the increasing rates of throat cancer in the UK, and the potential increase in cases where HPV is found in the tumour tissue. The specialists looked at a particular type of throat cancer called oropharyngeal squamous cell carcinoma and found that the incidence has increased from 7 per 100,000 men to 11 per 100,000 between 1989 and 2006.

Although this was the main point of the original editorial, the main point of the resulting media speculation has been the link to oral sex and the cervical cancer vaccination.

What evidence did they use to support their claims?

The main claim is that the increase in cases of oropharyngeal squamous cell carcinoma could be due to an increased prevalence of HPV.

They cited a Swedish study as the main support for this. This study looked at how many of these tumours contained HPV and found that although in 1970s only 23.3% of biopsies were positive for HPV, this figure rose to 93% between 2006 and 2007. A similar American study found slightly lower figures of 60-70% of tumours containing HPV.

The authors go on to mention that cancers containing HPV are slightly easier to treat with a survival rate of 87-5-95% compared to 62-67% in non-HPV-related tumours.

This means there is the potential that these two types of tumour - squamous cell carcinoma containing HPV and squamous cell carcinoma not containing HPV - may actually act differently, and require different treatments. May be they should be classified separately. There is currently no research on this.

What has this got to do with oral sex?

The authors do not substantiate the link between oral sex and HPV transmission. This seems to stem from the knowledge that HPV may be sexually transmitted. It seems to only have been applied to female to male transmission, completely excluding male to male, male to female and female to female.

The authors seems to feel that the link to oral sex is supported by the finding that a higher number of life partners correlates with an increased risk of throat cancer. This correlation was a 'borderline' finding and barely supportable by statistical analysis.

The authors do not comment on the main, established risk factors for oropharyngeal squamous cell carcinoma which are alcohol and smoking. It would seem obvious that a higher number of life partners implies a greater number of separations and periods of stress, which in turn might correlate with a higher usage of alcohol and tobacco. But no-one has commented on that.

The authors have not looked at sexual practices over the last thirty years to see whether they have changed. They have also not looked at rates of sexually transmitted HPV infection.

What about cervical cancer vaccination in boys to protect men from throat cancer?

There is no evidence that the current HPV vaccination offered to girls to protect them from cervical cancer needs to be given to boys. Even if HPV were found to ba causative agent for throat cancer, vaccinating girls should have an appreciable impact on incidence.

Conclusions

- Researchers have found that the rates of throat cancer in men have increased over the last thirty years or so. They do not comment on rates in women.

- Researchers have found that more samples of throat cancer contain HPV than thirty years ago.

- There is no evidence to suggest that HPV causes throat cancer.

- There is some evidence that tumours containing HPV react differently to treatment than those that do not.

- There is no evidence that increased rates of throat cancer are due to HPV transmission via oral sex.

- There is no evidence to suggest whether sexual HPV transmission has increased over the last 30 years.

- There is no evidence to suggest whether vaccinating either girls or boys will have any effect on rates of throat cancer.

The newspaper article that had caught my eye, had taken a slither of fact from this editorial, and created a series of statements that were linked to, rather than supported by the evidence. And the editorial itself had made some startling, unsubstantiated leaps of thinking. But this is an interesting area of work, and may provide important clues that help us to managed throat cancer more effectively in the future.

BBC Reviews Science Coverage

The BBC is to conduct a review of its science-related output following claims of bias in reporting issues such as climate change, genetically-modified food and the MMR vaccine.

The review, conducted by the BBC's governing body the BBC Trust, is a requirement of the Royal Charter and Agreement that states that the organisation must cover potentially controversial subjects, including science, with due impartiality.

The review will cover the natural sciences, as well as aspects of technology, medicine and the environment that involve scientific statements, research or claims made by scientists. It will focus on news and factual programming referring to scientific findings that might have political or policy-related implications.

News of the review has sparked concern amongst some BBC staff. However, BBC Radio reporter Richard Hollingham welcomed the move.

“For any reporter who works for the BBC, either as a freelancer or staff, balance and impartiality are in our blood. If anything, in recent years, we have been accused of being too balanced when it comes to covering climate change, perhaps sometimes giving the impression that scientific opinion was split 50/50 by featuring discussions with climate scientists versus sceptics,” he said.

"I'd welcome any review. There's no harm in questioning the way the BBC reports science. The BBC is under unprecedented political pressure at the moment from politicians and vested media interests so I don't think we should get too worked up about this.”

The review is expected to begin in the spring, with the findings published in 2011. It comes at a time when the BBC Executive has indicated the desire to raise the profile of science across the BBC’s television, radio and online outlets.

Further coverage:

Media Guardian

Journalism.co.uk

Metabolism

Metabolism describes all the chemical reactions occurring within our bodies, keeping our cells and tissues functioning.

Originating from the Greek (meta- meaning ‘over’ and -ballein ‘to throw’), it has come to mean a process of change. In the context of our bodies, metabolism refers to the rate at which we are burning energy or calories, and this process is broadly controlled by the thyroid gland in the neck.

Our metabolic rate changes constantly - it slows at night and speeds up in the day. Our overall metabolic rate is largely determined by genetics. Health or diet products that speed it up artificially can be really bad news for active organs like the brain and heart. One thing that we can do to burn more energy is have a hearty breakfast – this helps to kick the body out of the slower nocturnal metabolism into the calorie-burning day mode!

CT Scan

Computed axial tomography (CAT) is essentially a complex and more detailed form of the traditional X-ray. Tomography means ‘picture slices’ (from the Greek tomos mean- ing ‘slice’ and graphein meaning ‘to write’).

In the CT or CAT scanner, horizontal (or axial) ‘pictures slices’ are taken of the body. The CT scanning machine looks like a giant polo mint with a bed passing through the central hole. The large white ring structure houses the X-ray beam, with the detecting device on the opposite side. These both rotate around the patient on the bed, allowing full ‘slice’ images to be taken of the body.

The data recorded is quite complex and hence requires computational analysis to make the scan images that doctors use to diagnose diseases. In addition to producing a series of two-dimensional images, computer manipulation can add the images together to produce three-dimensional representations of the body and internal organs.

MRSA (Methicillin-Resistant-Staphylococcus-Aureus)

This hospital superbug is a strain of the common Staphylococcus aureus bacterium. It often lives on the human body without causing harm but when the body’s defences are weakened, it may cause an infection.

Individually, the bacteria appear spherical (-coccus from the Greek kokkos, meaning ‘berry’ or ‘grain’), but they can arrange themselves in groups or colonies shaped like bunches of grapes (staphylo- from the Greek word staphyle, meaning ‘bunch of grapes’) and in laboratory culture appear yellowish (aureus from Latin meaning ‘golden’).

MRSA has developed a defence against penicillin-type antibiotics (it is methicillin-resistant). It produces an enzyme (called β-lactamase), which breaks down the crucial central structure of the drug, preventing it from killing the bacteria.

MRSA (Methicillin-Resistant-Staphylococcus-Aureus)

This hospital superbug is a strain of the common Staphylococcus aureus bacterium. It often lives on the human body without causing harm but when the body’s defences are weakened, it may cause an infection.

Individually, the bacteria appear spherical (-coccus from the Greek kokkos, meaning ‘berry’ or ‘grain’), but they can arrange themselves in groups or colonies shaped like bunches of grapes (staphylo- from the Greek word staphyle, meaning ‘bunch of grapes’) and in laboratory culture appear yellowish (aureus from Latin meaning ‘golden’).

MRSA has developed a defence against penicillin-type antibiotics (it is methicillin-resistant). It produces an enzyme (called β-lactamase), which breaks down the crucial central structure of the drug, preventing it from killing the bacteria.

Epidemic/Pandemic

Is it a pandemic or an epidemic of flu that hits the headines from time to time, with journalists

speculating that it could wipe out the human race?

Well, the words mean much the same thing - an outbreak of disease. They have the same ending (-demic, which is derived from the Greek demos meaning people). However, a pandemic affects people all over the world (pan- meaning all), whereas epidemics (epi- meaning upon or among) are usually thought of as affecting a smaller group of people (all pupils at a school, all people in a particular area or even the population of a whole country).

These words are used by epi-demiologists - who study factors affecting the health and illness of populations - to describe how a disease such as flu (or, in the olden days, bubonic plague) is spreading around the world. The words imply the scale, rather than severity, of the problem.