The other half of the HPV story

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HPV vaccination was initially seen as a program for girls, and for good reason. The human papilloma virus is the primary cause of cervical cancer, and the early vaccination programs were designed with that in mind. Then it became clear that boys needed to be included too, since they could transmit the virus when they became sexually active. Australia was ahead of the curve here, adding boys to the National Immunisation Program in 2013. But the case for vaccinating boys has just become considerably stronger.

It is now well established that males are susceptible to HPV-related cancers in their own right. These include cancers of the throat and pharynx, which are rising in Australian men, as well as penile and anal cancers, and evidence suggesting oesophageal cancer may be linked to HPV as well. Oropharyngeal cancer rates have been increasing steeply in Australian males for decades, and HPV is now understood to be the dominant driver.

There is a double benefit in vaccinating boys. It reduces their own cancer risk at multiple sites, and it brings Australia closer to making cervical cancer a disease of the past.

A large study published in JAMA Oncology followed over 615,000 boys who had been vaccinated against HPV and compared them to over two million who had not, tracking cancer outcomes up to the age of 26. What makes this finding particularly striking is the timeframe. HPV-related cancers typically have a latency period of 20 years or more, meaning the full protective effect of vaccination in adolescence won't be visible for decades. Yet even within this relatively short follow-up period, vaccination was associated with a 46 per cent lower risk of developing HPV-related cancers. Among boys vaccinated between the ages of nine and 14, the reduction was 42 per cent. Among those vaccinated between 15 and 26, it reached 50 per cent.

The cancers assessed included head and neck, oesophageal, anal and penile cancers. The consistency of the protective effect across all of these sites strengthens the case considerably.

There is also the bigger picture to consider. Australia has set itself the goal of eliminating cervical cancer entirely, and vaccination of boys is a critical part of getting there. Boys and men transmit HPV to women, so male vaccination reduces the viral load circulating in the population, directly lowering women's risk of cervical cancer. The vaccine's reach doesn't stop there. Cervical screening in Australia now tests for the virus itself rather than just abnormal cells, with five-yearly screening for those who test negative and closer monitoring for those who don't. Vaccination combined with high screening participation and prompt treatment of early findings is what makes elimination genuinely achievable.

There is a double benefit in vaccinating boys. It reduces their own cancer risk at multiple sites, and it brings Australia closer to making cervical cancer a disease of the past. Given that the protective effect seen in this study is almost certainly the floor rather than the ceiling, the argument for early vaccination in both sexes has rarely been stronger.