Oropharyngeal squamous cell carcinomas originate in the soft palate, tonsils, base of tongue, pharyngeal wall, or the vallecula, the fold located between the base of tongue and the epiglottis (figure 1) . Oropharyngeal cancer is a relatively uncommon malignancy, with approximately 123,000 cases of oropharyngeal and hypopharyngeal cancer diagnosed worldwide each year, which cause about 79,000 deaths .
Historically, tobacco and alcohol were the principal risk factors associated with oropharyngeal cancer. However, there has been a shift in the epidemiology of this disease, with a significant increase in cases due to human papillomavirus (HPV) infection and a decrease in cases associated with tobacco and alcohol . These HPV associated cancers predominantly arise in the oropharynx, particularly the tonsillar area and the tongue base. Although these tumors have significant differences compared with other cancers arising in this area, including better prognosis, there is no evidence to indicate that treatment is different from that with other oropharyngeal tumors. Current clinical trials either stratify for HPV status or are designed specifically for patients with HPV associated cancer, to answer questions related to minimizing treatment-related toxicities. (See "Human papillomavirus associated head and neck cancer".)
The tumor node metastasis (TNM) staging system of the American Joint Committee on Cancer (AJCC) and the International Union for Cancer Control (UICC) is used to stage oropharyngeal cancer (table 1 and figure 2) . (See "Overview of the diagnosis and staging of head and neck cancer".)
The treatment of locally advanced, stage III to IVB (table 1) cancers of the oropharynx will be reviewed here. The treatment of early stage oropharyngeal cancer is discussed separately, as is the management of patients with distant metastases (stage IVC).
●(See "Treatment of early (stage I and II) head and neck cancer: The oropharynx", section on 'General principles'.)