Chapter 1 - Epidemiology, Risk Factors and Pathogenesis of Squamous Cell Tumours
- HNSCC encompasses a heterogeneous group of upper aerodigestive malignancies originating in the lip, oral cavity, pharynx and larynx
- It is the sixth most common cancer worldwide, accounting for 1%–2% of all cancer-related deaths
- Historically, HNSCC has been associated with tobacco smoking and alcohol use
- Globally, the incidence of tobacco-related HNSCC is associated with patterns of tobacco use and is decreasing in countries with declining rates of tobacco consumption
- In the past decade, infection with high-risk HPV and especially with HPV16 has been implicated in the pathogenesis of a growing subset of HNSCCs, mainly those arising from the oropharynx
- HPV-related OPC represents a distinct entity in terms of biology and clinical behaviour
- Five-year survival rates for all stages of HNSCC is approximately 65%. High cure rates are reported with localised and locoregional disease, but prognosis is dismal for recurrent or metastatic disease
- For HNSCC, malignant transformation of normal mucosa to invasive carcinoma follows a molecular progression model of multistep carcinogenesis
- Tobacco-related HNSCC demonstrates mutation of the p53 gene and downregulation of the p16 protein
- On the contrary, HPV-associated OPC is typically characterised by wild-type p53 and Rb genes and upregulation of p53 protein levels
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