Squamous Cell Carcinoma of the Tongue
Carcinoma of the oral tongue (that portion of the tongue anterior to the circumvallate papillae) encompasses 75% of all tongue cancers and is the most common intraoral malignancy (excluding the lip, which is generally not considered to be intraoral and in which the carcinogen is different). Oral tongue carcinomas account for 20% to 30% of all intraoral cancers.
The most common location is the lateral border in the area of the lingual tonsils. The left side is more common than the right (61% to 39%), ostensibly because the greater number of right-handed smokers aim the smoke stream toward the left side.
The lesions will be red-white in color but may appear only as clinical leukoplakia (all white), be exophytic or be ulcerated.
Some lesions will be indurated (firm to palpation), which is indicative of tumor cells infiltrating between the muscle fibers of the tongue.
About 60% are painless, as cancer by itself is indeed painless. However, 40% present with pain due to the advanced stage of the disease, cancers are painful because they invade and expose areas of high nerve-end density, such as periosteum, or become secondarily infected.
An ulcerated lesion on the tongue is a classic differential diagnosis. Certainly squamous cell carcinoma is the primary consideration, but other diseases can also be represented by a tongue ulcer. In particular, oral tuberculosis (TB)-associated ulcers related to pulmonary TB and systemic fungal diseases such as histoplasmosis and coccidioidomycosis originating from a lung focus may produce a tongue ulcer as well. Trauma remains a common cause of tongue ulcers. The rare traumatic eosinophilic granuloma occurs most often on the tongue and will also present with induration. Some cases of primary syphilis (chancre) may also mimic a red-white patch or ulcer suggestive of carcinoma.
A clinical oral and head and neck examination should be followed by a mirror or fiberoptic examination of the laryngopharynx and then a TNM staging and incisional biopsy.
Debate exists about whether surgery or radiation is the best primary mode of therapy. When handled correctly, either one is as effective as the other for tumor control. The debate more or less involves side effects and morbidity. It is our opinion that surgery is the preferred modality and that postoperative radiotherapy is a distinct consideration in many cases. The type of surgery performed, the decision to use radiotherapy postoperatively or even preoperatively, and whether and/or how to treat the neck depend on many factors such as the clinical staging, the patient’s ASA risk, the thickness of the tumor, the histologic grade, and histologic features related to perineural or perivascular spread, among others. Generally, the primary tumor is excised with 1.5-cm margins. For lesions with a depth of invasion 4 mm or greater, treating the neck prophylactically with either an incontinuity functional neck dissection or radiotherapy in a dose of 5,000 cGy to 6,500 cGy is recommended. For nodal disease of N1, a functional neck dissection is recommended. For nodal disease of N2 or N3, most believe that a modified radical neck dissection is preferred, followed by postoperative radiotherapy from 5,000 cGy to 6,500 cGy.
Prognosis and follow-up
The prognosis for oral tongue squamous cell carcinoma varies according to many factors, particularly the TNM staging, the thickness of the primary tumor, evidence of perineural spread, lymph node capsular invasion, and intralymphatic emboli. Taken all together, adjusted 5-year survival rates are between 40% and 60%.
Patient follow-up, re-examination occurs every 4 months for the first 2 years followed by every 6 months thereafter. Follow-up should include a chest radiograph once a year and a mirror oropharyngeal examination.