An ICEP paper has been published online in BMC Medicine 'Investigating the effect of sexual behaviour on oropharyngeal cancer risk: a methodological assessment of Mendelian randomization'.

Lead author Mark Gormley summarises the paper:

Human papilloma virus infection is known to influence oropharyngeal cancer risk, likely via sexual transmission. However, sexual behaviour has been correlated with other risk factors including smoking and alcohol, meaning independent effects are difficult to establish.

Using univariable Mendelian randomization, we found evidence supportive of an effect of both later age at first sex and number of lifetime sexual partners on oropharyngeal cancer risk. However, there was some attenuation of these in the multivariable models and negative control analyses suggested potential violation of the core MR assumptions. Subsequent CAUSE analysis implicated pleiotropy of the genetic instruments used to proxy sexual behaviours. This study emphasises a need for multivariable approaches and the triangulation of evidence when performing MR of complex behavioural traits.