Human papillomavirus: the biology of carcinogenesis


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Ned Powell1
1Cardiff University, Cardiff, UK

Abstract

Human papillomavirus (HPV) is the primary cause of nearly all cervical cancers. Since the sexual revolution of the 1960s, the prevalence of HPV has increased dramatically, such that approximately one in three women in their twenties are currently infected. Fortunately, measures to prevent HPV-associated disease have also developed rapidly, initially based on cytological screening in women and more recently on prophylactic vaccination in young girls.

In the last decade, awareness of the wider disease burden attributable to HPV, especially in men, has increased. It is now apparent that the increased incidence of oropharyngeal cancers (predominantly tonsil and base of tongue) is also attributable to HPV. In the USA, current data suggests that by 2020 the annual incidence of HPV-positive oropharyngeal cancers will exceed the annual incidence of cervical cancers. UK data show similar trends.

HPV-positive oropharyngeal cancers affect a different demographic group (generally younger, fitter men), and show markedly different clinical behaviour, to tumours associated with long-term tobacco and alcohol use. There is hence an urgent need to understand the biology of HPV in the oropharynx and determine whether tumours with a viral aetiology require different treatment to tumours associated with chemical carginogenesis.

In the cervix, HPV exists primarily within an intraepithelial compartment and is regarded as being highly effective at hiding from the immune system. In tonsillar infections however, HPV causes proliferation in an environment with much greater exposure to the immune system. This talk will introduce the epidemiology and basic biology of HPV-associated carcinogenesis with a focus on the role of the immune system in controlling infection and proliferation.