Head and neck cancers rank as the sixth most common cancer worldwide.
Risk factors include:
- Male gender
- Increasing age
- Strong history of smoking and drinking
About 90% of head and neck cancers are squamous cell carcinomas (HNSCC). With the decline in smoking and drinking with public health measures, the incidence of HNSCC has been decreasing.
Despite the overall decline in incidence of HNSCC, the incidence of oropharyngeal SCC has been steadily increasing, particularly in developed countries. Oropharyngeal SCC is driven by human papilloma virus (HPV) infection. Oropharyngeal cancer commonly present as an isolated neck mass without any symptoms.
Tonsils and tongue base are the primary sites most associated with a HPV+ve oropharyngeal SCC. They tend to be seen in younger (40s to 50s) patients with little smoking and/or drinking history. Several studies have shown that HPV+ve oropharyngeal SCC patients have significantly improved overall and disease-free survival compared to patients with HPV-ve oropharyngeal SCC. Thus diagnosis of HPV+ve oropharyngeal SCC represents better prognosis.
HPV expresses E6 and E7 proteins. E6 inactivates p53, and E7 inactivates Rb. Both p53 and Rb have a role in tumour suppressor functions. Upregulation of p16 is seen with functional inactivation of Rb by E7. Thus p16 is commonly used as a surrogate marker for HPV infection. HPV 16 is strongly associated with oropharynx SCC.