Vaccination against HPV: a story of cancer prevention in 2 parts

The size of problem

Over four decades have passed since Human papillomavirus (HPV) was first linked to cervical cancers. HPV is now established as the fundamental cause of nearly all cervical cancers and as a major contributor to many other anogenital cancers, especially anal cancers. Worldwide, HPV is the cause of 5% of all cancers. Vaccination to prevent HPV infection promises to dramatically reduce this disease burden.

The path to vaccination

Two areas of research have made vaccination possible. Firstly, epidemiological studies to understand which types of HPV cause cancer, and how common they are in various populations, and secondly development of virus-like-particle (VLP) vaccines against the relevant HPV types. In 2008, UK HPV vaccination was introduced for 12-13 year-old girls.

This decision was underpinned by data generated by the Cardiff University HPV Research Group, led by Professor Alison Fiander, Dr Ned Powell and Dr Sam Hibbitts,  which defined the prevalence of HPV in the Welsh population, and the HPV types present in cervical cancers diagnosed in Welsh women. This showed that approximately 30% of women in their early twenties carried a genital HPV infection, and that 80% of cancers could be prevented using current vaccines. This evidence was highly persuasive in making the case for UK wide vaccination of young girls.

A sub-plot takes centre stage

Many people were aware of the link between HPV and cervical cancer, but in 2010, international studies suggested a strong link to oropharyngeal cancers too, especially tonsil cancers. Initial studies by Professor Mererid Evans (a consultant oncologist at Velindre Cancer Centre) and Dr Powell, showed HPV to be implicated in 55% of oropharyngeal cancers diagnosed in Wales.

Unlike cervical cancers, there is no screening programme to prevent oropharyngeal cancers and it soon became apparent that incidence of HPV-associated cancers was increasing at an alarming rate – indeed faster than for any other cancer in the UK. Furthermore, most of these cancers occur in men, who were not directly protected by vaccination of young girls.

A case for vaccinating boys was growing, but there was a lack of evidence to support it. In 2016 Dr Powell, Professor Evans and collaborators from Liverpool University, published an investigation of incidence of HPV-driven oropharyngeal cancers across the UK, which showed that incidence had doubled in the preceding decade and that the majority of these cancers were caused by HPV. This data challenged the assumptions that had previously led to vaccination of boys being considered not cost effective.

This is a shortened version of the full article that features in edition 33 of ReMEDy.

Read the full article