Increased risk of oropharyngeal cancers mediated by oral human papillomavirus infection: Results from a Canadian study.

Background This study aimed to estimate the extent to which oral sex behavior is associated with an increased risk of oropharyngeal cancers (OPCs), and how much of the association is mediated by oral human papillomavirus (HPV) infection. Methods We used data from a hospital-based case-control study conducted in Montreal, Canada. Information on oral sex behaviors was collected. Oral rinse and oral brush specimens were analyzed for HPV positivity and genotyping. Logistic regression estimated the odds ratios (OR) and 95% confidence intervals (CI) for the association between oral sex behaviors and OPC. Results Onset of oral sex practice at age 16 years or younger had an increased risk of OPCs relative to those with onset after age 30 years (OR = 2.98; 95% CI 1.37-6.47). This association decreased (OR = 1.09; 95% CI 0.25-4.71) when restricted to those positive for HPV. Conclusions Our results suggest that the association between oral sex and OPC seems mediated by oral HPV infection.