Another reason to vaccinate boys and young men against HPV

There is a clear established causal link between human papillomavirus (HPV) infection and development of cervical cancer in women.
 
According to the Cancer Council, HPV is also responsible for almost all cases of genital warts, along with 90% of anal cancers, 35% of penile cancers and 60% of oropharyngeal cancers.
 
Now, new research has found a causal link between HPV and prostate cancer in men.
 
The research, published in Infectious Agents and Cancer, reviewed results from 26 previous studies on HPVs and their links to prostate cancer.
 
Among its findings, it noted recent studies reported that 231 of 1071 prostate cancers (21.6%) were HPV-positive, while only 74 of 1103 benign prostate controls (6.7%) were HPV-positive.
 
‘HPV infections may initiate prostate oncogenesis directly and influence oncogenesis indirectly,’ the authors wrote.
 
The authors note HPVs are only one of the many pathogens that have been identified in prostate cancer. They add, however, that this finding is important because they are the only vaccine-preventable infectious pathogen.
 
Professor James Lawson from the University of New South Wales was the lead researcher of this review. He told newsGP these findings should strengthen the call for boys and young men to be vaccinated against HPV for the sake of their own health.
 
‘We’ve been able to show – we think conclusively – that HPV is involved in prostate cancer,’ he said.
 
‘The action following this work is simple: encourage boys as well as girls to have the HPV vaccine.
 
‘Boys and young men should be encouraged to be vaccinated against HPV infections, exactly the same as girls.’
 
That is not currently happening in Australia.
 
While HPV vaccination rates are improving in both sexes, according to the National Cancer Control Indicators, females are still being vaccinated at a greater rate than males.
 
The uptake for all three doses of HPV vaccinations in females aged 15 years increased from 71.9% in 2012, to 80.2% in 2017.
 
Meanwhile, the uptake of all three doses in males aged 15 years increased from 62.4% in 2014, to 75.9% in 2017.
 
Professor Lawson hopes these new findings will help to close that gap.
 
‘The assumption has been that HPV infections and cervical cancer is women’s business – it’s not. It’s also men’s business,’ he said.
 
But it was not always considered men’s business.
 
While the Therapeutics Goods Administration (TGA) approved the HPV vaccine Gardasil for use in Australia in 2006, and rolled out a national HPV program the following year, it was not until 2013 that the Australian Government extended the vaccination program to include teenage boys.
 
Long before then, Professor Lawson wondered whether there was a link between HPV and prostate cancer.
 
He says the seeds for this new research were sown more than 20 years ago, when one of his postgraduate students discovered that the prevalence of breast cancer increased markedly and rapidly among women who migrated from China and Japan to Australia and the US.
 
‘So I thought, “That means breast cancer must be caused by something external”,’ Professor Lawson said.
 
Upon further investigation, Professor Lawson and his team discovered a viral link to breast cancer. They then decided to see if there was a similar link between viruses and prostate cancer.
 
‘And we showed exactly the same thing,’ he said.
 
Right from the start of this research, Professor Lawson says it was evident HPV was found in men with prostate cancer.
 
‘The difficulty was in proving that it was causal, as distinct from just being there,’ he said. ‘And we’ve been able to do that.’
 
The exact mechanisms that cause HPV to lead to prostate cancer are ‘incredibly complicated’.
 
One such mechanism may involve a family of enzymes known by its acronym, APOBEC, which have evolved to protect mammals against viral infections.
 
‘And it’s been discovered that HPV adversely influence the role of APOBEC enzymes and, as a consequence, people with HPV infection are at risk of developing various cancers,’ Professor Lawson said.
 
‘It’s really an extraordinary story.’
 
Professor Lawson hopes to spread the message regarding the importance of HPV vaccination in males.
 
‘The serious implication of this study is that boys should get vaccinated at a high rate exactly the same as girls,’ he said.
 
‘That’s a very strong message for medical practitioners.’

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HPV human papillomavirus prostate cancer vaccine