Cancer Health Center

Oropharyngeal cancer is uncommon and typically involves patients in the fifth through seventh decades of life; men are afflicted 3 to 5 times more often than women.[1,2,3]

Similar to other cancers of the head and neck, tobacco and alcohol abuse represent the most significant risk factors for the development of oropharyngeal cancer.[3,4] (Refer to the PDQ summaries on Hypopharyngeal Cancer Treatment and Lip and Oral Cavity Cancer Treatment for more information.) Other risk factors may include:[5]

• A diet poor in fruits and vegetables.[6]
• The consumption of mat�, a stimulant beverage commonly consumed in South America.[7]
• The chewing of betel quid, a stimulant preparation commonly used in parts of Asia.[8]
• Infection with the human papillomavirus (HPV), especially HPV-type-16, also known as HPV-16.[9,10,11]

Defective elimination of acetaldehyde, a carcinogen generated by alcohol metabolism, poses an additional risk factor for oropharyngeal cancers. In individuals, primarily East Asians, carrying an inactive mutant allele of alcohol dehydrogenase-2, alcohol consumption is associated with a susceptibility to multiple metachronous oropharyngeal cancers that are caused by the decreased elimination of acetaldehyde.[12]

Anatomically, the oropharynx is located between the soft palate superiorly and the hyoid bone inferiorly; it is continuous with the oral cavity anteriorly and communicates with the nasopharynx superiorly and the supraglottic larynx and hypopharynx inferiorly. The oropharynx is divided into the following sites:[13]

• Base of the tongue, which includes the pharyngoepiglottic folds and the glossoepiglottic folds.
• Tonsillar region, which includes the fossa and the anterior and posterior pillars.
• Soft palate, which includes the uvula.
• Pharyngeal walls, that is, posterior and lateral.

The regional lymph node anatomy of the head and neck contains lymph nodes that run parallel to the jugular veins, spinal accessory nerve, and facial artery and into the submandibular triangle; an understanding of this anatomy and the status of regional lymph nodes is critical to the care of head and neck cancer patients.[3,14] The regions of the neck have been characterized by levels (I-V) to facilitate communication regarding the lymph node anatomy:

• Level I contains the submental and submandibular lymph nodes.
• Level II contains the upper jugular lymph nodes, which are above the digastric muscle.
• Level III contains the mid-jugular lymph nodes, which are between the omohyoid muscle and the digastric muscle.
• Level IV contains the lower jugular lymph nodes.
• Level V contains the lymph nodes of the posterior triangle.

Histologically, almost all oropharyngeal cancers are squamous cell carcinomas (SCCs).[3] Other cancers in this area include minor salivary gland carcinomas, lymphomas, and lymphoepitheliomas, also known as tonsillar fossa. (Refer to the PDQ summaries on Salivary Gland Cancer Treatment, Adult Hodgkin Lymphoma Treatment, and Adult Non-Hodgkin Lymphoma Treatment for more information.)