Oropharyngeal Cancer Treatment (PDQ®): Treatment - Health Professional Information [NCI] - General Information About Oropharyngeal Cancer
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:
- 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, i.e., 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.[3,27] 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.
- Retropharyngeal lymph nodes.
Traditionally, the retropharyngeal lymph nodes are at risk for nodal spread in oropharyngeal cancer; this incidence has not been well established until recently.
In a large, retrospective cohort from the MD Anderson Cancer Center, 981 oropharyngeal patients who underwent primary radiation therapy were analyzed. The base of the tongue (47%) and the tonsil (46%) were the most common primary sites. The majority of patients had stage T1 to T2 primary tumors (64%), and 94% had stage 3 to 4B disease. The incidence of radiographic retropharyngeal-nodal involvement was 10% and was highest for the pharyngeal wall (23%) and lowest for the base of the tongue (6%). Retropharyngeal lymph-node involvement was associated with inferior 5-year local control and inferior recurrence-free, distant metastases-free, and OS on multivariate analysis.[Levels of evidence: 3iiA, 3iiDii] Histologically, almost all oropharyngeal cancers are SCCs. 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.)