Squamous cell carcinomas of head and neck mucosal (HNSCC) sites remain the sixth most commonly occurring cancers world-wide. A significant proportion of these tumours (particularly of the oropharynx) are directly attributable to the human papillomavirus (HPV). The increase in incidence of HPV-related tumours has been postulated to be due to changing sexual practices in the community. Contributory factors including younger age at sexual debut, increased lifetime number of sexual partners, and ever having had oral sex, have all been associated with an increased risk of HPV-related tumours of the head and neck.
Materials and Methods:
We analysed 136 formalin-fixed paraffin-embedded squamous cell carcinomas from the oral cavity (n=40) and oropharynx (n=96) recruited from the Princess Alexandra Hospital (Brisbane, Australia). Samples were analysed for the presence of HPV DNA using a combination of the mucosal HPV general primer GP+ PCR and sequencing; p16INK4a expression was assessed by immunohistochemistry. Each patient completed a questionnaire detailing their lifestyle factors such as tobacco smoking and alcohol consumption; marital status, and their sexual behaviour and history.
HPV DNA prevalence in oral cavity cancers was 5%, and 72% in the oropharyngeal cancers (p<0.0001). HPV-16 was the most commonly detected HPV type (found in 91% of all HPV-positive tumours). There was a strong correlation between HPV DNA positivity and positive p16INK4a staining in oropharyngeal tumours (p<0.0001). Having a HPV-related tumour was associated with being married currently or previously (p=0.046), increasing number of passionate kissing partners (p=0.046), ever having given oral sex (p=0.0007) and with increasing number of oral sex partners (p=0.0015).
This study found a higher prevalence of HPV in oropharyngeal than oral cavity tumours, with a strong association identified between oral sex behaviours and HPV-positive tumours. Further research is needed to establish that vaccines will reduce transmission and carriage of oropharyngeal HPV infections.