The concept of field cancerization may be responsible in part for the multiple, synchronous primary SCCs that occur in oropharyngeal cancer and are associated with a smoking history. This concept, originally described in 1953, proposes that tumors develop in a multifocal fashion within a field of tissue chronically exposed to carcinogens. Molecular studies detecting genetic alterations in histologically normal tissue from high-risk individuals have provided strong support for the concept of field cancerization.[30,31,32,33,34]
Clinically, cancers of the base of the tongue are insidious. These cancers can grow in either an infiltrative or exophytic pattern. Because the base of the tongue is devoid of pain fibers, these tumors are often asymptomatic until they have progressed significantly.
Symptoms of base-of-the-tongue cancers may include the following:[3,26]
- Referred otalgia secondary to cranial nerve involvement.
- Trismus secondary to pterygoid muscle involvement.
- Fixation of the tongue that is caused by infiltration of the deep muscle.
- A mass in the neck.
(Refer to the PDQ summary on Pain and for more information on weight loss; also refer to the Nutrition in Cancer Care summary.)
Lymph node metastasis is common because of the rich lymphatic drainage of the base of the tongue. Approximately 70% or more of the patients have ipsilateral cervical nodal metastases; 30% or fewer of the patients have bilateral, cervical lymph-node metastases.[26,35] The cervical lymph nodes involved commonly include levels II, III, IV, V, and retropharyngeal lymph nodes.
The symptoms of tonsillar lesions may include the following:[3,26]
- Weight loss.
- Ipsilateral referred otalgia.
- A mass in the neck.
The anterior tonsillar pillar and tonsil is the most common location for a primary tumor of the oropharynx. Lesions involving the anterior tonsillar pillar may appear as areas of dysplasia, inflammation, or a superficial spreading lesion. These cancers can progress across a broad region including the lateral soft palate, retromolar trigone and buccal mucosa, and tonsillar fossa.[3,26] The lymphatic drainage is primarily to level II nodes.