Oral and oropharyngeal cancer and the role of sexual behaviour: a systematic review: Beyond the Abstract

Over the last decade there has been a steady increase in the incidence of oropharyngeal cancer (OPC) in many developed countries. This observed trend is in contrast to stable or falling rates of oral cavity cancers in developed countries.

The main risk factors for oral cavity and oropharyngeal cancer are tobacco smoking and alcohol consumption. However a rising number of the OPCs diagnosed today are in a younger population, who are non-smokers and drink only modest amounts of alcohol. 

Molecular analysis of this sub-group of cancers often reveals the Human papillomavirus or HPV as the oncogenic catalyst, the same virus that causes virtually all cases of cervical cancer. 

One theory is that this rise in OPC incidence is due to a change in sexual behaviour that began in the Western world between the 1960s-1980s, a time referred to as the sexual revolution. This change in sexual behaviour, particularly oral sex, is thought to have led to an increase in the transmission of genital HPV to the oral cavity and oropharynx. Susceptible individuals are unable to clear the virus, leading to the rise in HPV positive head and neck cancers, primarily OPCs. 

The question is: what is the evidence for sexual behaviours being risk factors for OPC? And how strong is this evidence? 

The aim of this review was to systematically search the literature, identifying and critically evaluating the current evidence for the association between sexual behaviours and OPC. We were unable to perform a meta-analysis given the differences in the individual study designs.

In the early studies, that included both oral cavity cancers and oropharyngeal cancers, there was conflicting results on whether certain sexual behaviours increase the risk of oral cancer, with one study’s surprising finding that oral sex reduced the risk of oral cancer development.

However more recent studies have focused on oropharyngeal cancer alone and have found that a high number of sexual partners, ever performing oral sex and a having a wife with a history of cervical cancer are associated with an increased risk of OPC. For other sexual behaviours eg number of lifetime oral sexual partners, the evidence is limited and further studies, particularly long-term prospective studies, are needed to confirm that certain sexual practices are potentially carcinogenic.

Currently New Zealand offers a fully-funded HPV vaccine to all young girls for protection against genital warts and cervical cancer. However the vaccine is not government funded for young boys. This is set to change in January 2017. Australia is already providing a fully funded HPV vaccination campaign for both sexes due to the potential benefits in reducing both male and female cancers and already Australia has seen a reduction in the incidence of high-grade cervical abnormalities in girls under 18 years of age and a decrease in genital warts in heterosexual men and women, with more evidence mounting of their highly successful immunisation programme.

Despite this success the health sector should not rely on vaccination alone to fight HPV and other preventative strategies such as the provision of subsidized oral sex barriers or dams to sexually active teens and young adults may help minimise the spread of this carcinogenic virus. Alternatively the health sector could discourage the act of oral sex entirely, explaining the hazards of such behaviour. The current evidence suggests the importance of being faithful to ones partner in order to reduce your risk of OPC.

Written by: James Chancellor

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