AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

The management of malignant neoplasms of the tongue base remains difficult despite recent advances in surgical techniques and multidisciplinary treatment programs. Many patients present at an older age with advanced disease because of the occult nature of associated symptoms. The disease process and treatment often affect adjacent structures, such as the larynx. Clinical outcome is determined primarily by histology, extent of disease, and treatment modality.

Careful multidisciplinary assessment and treatment selection based on the probability of cure and preservation of function are of paramount importance in the treatment of these patients. High recurrence rates, poor survival, and significant alterations in speech and swallowing function are common experiences for patients with malignancies in these anatomic sites. Despite these frustrations, patients are potentially curable and should be offered regimens that carefully consider morbidity and outcome within the context of the patient's overall medical condition.

Etiology

Risk factors for the development of base of tongue carcinoma include chronic alcohol and tobacco use, older age, geographic location, and family history of upper aerodigestive tract cancers. Environmental exposure to polycyclic aromatic hydrocarbons, asbestos, and welding fumes may increase the risk of pharyngeal cancer. Nutritional deficiencies and infectious agents (especially papillomavirus and fungi) also may play a significant role.

Pathophysiology

The base of the tongue plays a critical role in speech and swallowing. During the pharyngeal phase of swallowing, food and liquid are propelled toward the oropharynx from the oral cavity by the tongue and muscles of mastication. The larynx is elevated, effectively compressing the epiglottis and supraglottic larynx against the base of the tongue and forcing food, liquid, and saliva into the hypopharynx and cervical esophagus. The anatomic location of the hypoglossal nerve within the base of the tongue puts it at risk from invasion or compression from malignant neoplasms at the primary site or metastatic disease in the neck.

Although the larynx produces sound, the tongue and pharynx are the primary organs that shape sound into intelligible speech. Any alteration in tongue and pharynx mobility is immediately recognized as altered speech. Any loss of tissue from the base of tongue area prevents a watertight closure with the larynx during the act of swallowing. This mismatch allows food and liquid to escape into the pharynx and larynx, altering the carefully choreographed swallowing reflex and often resulting in aspiration. Both neurologic impairment and alteration in the coordinated act of swallowing from malignancies in this area can have devastating affects on speech and swallowing ability.

Clinical

The most common symptoms associated with malignant neoplasms of the tongue base are dysphagia, odynophagia, sensation of a mass in the throat, or the presence of a mass in the neck. Patients also may complain of referred ear pain or hemoptysis. Delay in diagnosis is not uncommon because of the common and sometimes vague nature of symptoms and the relative inaccessibility of the base of the tongue to examination. Upon physical examination, a mass is usually palpable in this area. Extensive submucosal disease or a strong gag reflex may make palpation more difficult. Patients may have bilateral palpable adenopathy because of the midline location and the high propensity for regional lymph node metastases. Indirect or flexible fiberoptic laryngoscopy in the office is a useful adjunct to the physical examination.

RELEVANT ANATOMY

Section 3 of 10  

• Authors and Editors
• Introduction
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

According to the American Joint Committee on Cancer, the base of the tongue is a subsite within the oropharynx and is bounded anterosuperiorly by the circumvallate papilla and the posterior aspect of the oral tongue (anterior two thirds), inferoposteriorly by the vallecula and lingual surface of epiglottis, and laterally by the glossoepiglottic folds.

Tongue development begins in the floor of the primitive oral cavity during the fourth embryonic week and develops from the region of the first 3-4 branchial arches. The tongue is eventually supplied by the lingual arteries and has complex capillary and venous systems.

Innervation of the tongue includes the lingual and hypoglossal nerves for sensation and movement and the sympathetic, parasympathetic, and special sensory fibers for salivation and taste ability. Tongue musculature includes both intrinsic and extrinsic muscles that contribute to the varied and subtle movements involved in speech and swallowing. Because the mucosa of the base of the tongue contains squamous epithelium, minor salivary glands, and lymphoid tissue, the histology of malignant neoplasms that arise from this region of the oropharynx is quite varied and sometimes confusing.

CONTRAINDICATIONS

Section 4 of 10  

• Authors and Editors
• Introduction
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Contraindications to surgical correction of malignant base of the tongue tumors are based on the patient's comorbidities and his or her ability to tolerate surgery. An obvious contraindication is patient refusal. Informed consent must be obtained prior to surgical intervention. Additionally, tumors may be considered inoperable because of their size (ie, extent) or location.

As is true with other sites of the head and neck, early-stage mucosal squamous cell carcinomas can be treated adequately with radiotherapy or surgical resection.

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Lab Studies

• The standard initial evaluation for distant metastases includes a chest radiograph and serum chemistry studies.
• • Chest radiographs have an approximate sensitivity and specificity of 50% and 94%, respectively, for the detection of pulmonary metastases.
  • Elevated serum levels of alkaline phosphatase are highly specific for the presence of bone metastases, but the sensitivity is low (20%).
  • Although serum liver function tests assess hepatic function, abnormal values are found in almost half the patients with head and neck cancer because of chronic alcohol use and, therefore, are of little value in identifying patients with liver metastases during the initial assessment. Modest elevation of liver function test results does not always require further investigation to exclude hepatic metastases.
• In general, obtain a chest CT scan if the chest radiograph yields abnormal findings; obtain a bone scan if the alkaline phosphatase level is elevated or symptoms are present; and perform an ultrasound, CT scan, or MRI on the liver when liver function test results are significantly elevated, depending on tumor stage and associated comorbidities.

Imaging Studies

• Patients in whom a malignant neoplasm of the base of the tongue is suggested should undergo an imaging study as part of their evaluation to aid in accurate staging of the primary site and necks.
• • CT scanning with intravenous contrast has been the standard imaging technique since its introduction.
  • MRI offers the advantages of finer tissue detail and multiplanar views and should be considered the imaging test of choice.
  • Chest radiographs are useful as a screening test for metastatic disease or a second primary malignancy.
  • Ultrasound is used in some parts of the world to assess tumor thickness.
  • Positron emission tomography (PET) alone or in combination with MRI is helpful when the diagnosis is unclear, in cases of unknown primary malignancy, or as a pretreatment assessment prior to nonsurgical treatment.
  • PET scanning is a new imaging technique that provides absolute and comparable quantitative data on tumor metabolism before and after chemotherapy. Radiolabeled fluorodeoxyglucose is used to measure metabolic activity. As tumor cells consume more glucose relative to surrounding normal cells, a difference in signal intensity can be identified. The presence of PET activity correlates with pathologic findings in patients with head and neck cancer. Elevated or rising PET activity after radiation therapy strongly suggests persistent or recurrent disease that may not be detected by CT scan or MRI.
  • Patients with hypopharynx or cervical esophagus cancer who are candidates for chemoradiation protocols should undergo PET scanning as part of their preoperative evaluation.

Diagnostic Procedures

• The extent of disease at the primary site, the status of the lymph nodes in the neck, and the evaluation for metastatic disease are vital to appropriate treatment planning. Examining a biopsy specimen obtained via endoscopic examination of the primary site with the patient under anesthesia remains the definitive procedure to establish the diagnosis and accurately assess the primary tumor.
• The indications for routine panendoscopy for the detection of second primary malignancies have significant geographic variation that is not based on differences in patient or tumor characteristics. There is substantial disagreement in the literature about the value of endoscopic screening for synchronous tumors. The prevalence rate of second primary malignancies of the upper aerodigestive tract varies from 3-15%, and the majority of tumors are detected within 2 years of initial presentation. Second primary malignancies are more common in patients with hypopharynx and esophageal carcinoma relative to other head and neck sites.
• • A higher detection rate is reported for patients undergoing routine panendoscopy. Others recommend regular endoscopic intervention within 2 years of treatment for optimum detection of second primary cancers.
  • Critics of routine screening esophagoscopy and bronchoscopy point out the low yield, potential for increased morbidity, questionable impact on expected survival and outcome, and cost in support of their position.
  • The decision regarding routine panendoscopy in the evaluation of hypopharynx and cervical esophagus cancer is currently at the discretion of the clinician.

Histologic Findings

The most common histology finding in patients with malignant neoplasms of the base of the tongue is squamous cell carcinoma. The physical appearance of these lesions can be confused with benign lesions, such as necrotizing sialometaplasia and ectopic gastric mucosa. Other less common histologies include neuroendocrine carcinomas, extrapulmonary bronchogenic carcinoma, typical and atypical carcinoid tumors, adenocarcinoma and adenosquamous carcinoma, basosquamous carcinoma, and lymphoepithelioma. Malignant transformation of a thyroglossal duct cyst may involve the tongue base secondarily.

Perineural invasion; vascular invasion; positive nodal status; extracapsular spread; contralateral, bilateral, or fixed nodes; level 4 or 5 positive nodes; and N2 disease are all significant predictors of lower survival, a higher incidence of neck recurrence, greater risk of distant metastases, and a poorer outcome.

Extranodal non-Hodgkin lymphoma of the head and neck is a relatively uncommon disease. If the nasopharynx (16%), tonsil (12%), and base of the tongue (8%) are grouped together, this combined site (Waldeyer ring) becomes the most common site of disease (36%). The majority of Waldeyer ring lymphomas express the B-cell phenotype. The clinical features and immunohistological findings suggest that Waldeyer ring lymphomas, other than those of the nasopharynx, share some of the characteristics of mucosa-associated lymphoid tissue lymphomas. In difficult cases, detection of monoclonal immunoglobulin, an absence of keratin staining, and a lack of epithelial features based on electron microscopy findings are useful adjuncts for diagnosis. Three fourths of the patients have stage I or II disease, and approximately two thirds of them have intermediate-grade lymphoma. Patients with lymphomas of high histopathologic grade and recurrent and disseminated disease have the poorest prognosis.

Other malignant histologies, including minor salivary gland cancer (eg, mucoepidermoid carcinoma, adenocarcinoma, adenoid cystic carcinoma), have been reported. Liposarcoma, leiomyosarcomas, and alveolar soft part sarcoma have been described in the base of tongue area, but these are rare.

Staging

Staging for malignant neoplasms of the base of tongue follows the guidelines described in the Manual for Staging of Cancer produced by the American Joint Committee on Cancer and is similar to staging of other subsites within the oropharynx. Staging of the primary site depends on the size of the lesion and the degree of involvement of adjacent structures. Note that staging of the neck for patients with malignant neoplasms of the base of the tongue is according to the American Joint Committee on Cancer criteria for tumors of the oropharynx.

• T1 - Tumor (T) smaller than 2 cm in greatest dimension
• T2 - Larger than 2 cm but smaller than 4 cm in greatest dimension
• T3 - Larger than 4 cm in greatest dimension
• T4 - Invades adjacent structures (eg, bone, soft tissue of neck, deep muscles of tongue)

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Medical therapy

The choice of treatment for patients with malignant neoplasms of the base of the tongue depends on a variety of factors. These factors include the clinical stage, histology, age, associated medical conditions, patient compliance, and potential adverse effects, complications, and outcomes. In order to allow the patient to make a reasonable and informed decision regarding treatment options, discuss these factors in detail before treatment.

Squamous cell carcinoma

Nonsurgical therapy for malignant neoplasms of the base of the tongue has garnered long-standing interest because of the significant potential morbidity associated with surgical resection. Historically, chemotherapy for squamous cell carcinoma of the head and neck has had limited success. Increased efficacy with platinum-based drugs and newer drug regimens has been demonstrated in the last 20 years. Typically, these experimental clinical protocols include radiotherapy as a major component of the treatment plan. Curative chemotherapy given as single-modality treatment for squamous cell carcinoma of the base of tongue, regardless of clinical stage, is uncommon and is not recommended at the present time.

As is true with other sites of the head and neck, early-stage mucosal squamous cell carcinomas can be treated adequately with radiotherapy or surgical resection. With increasing tumor stage, cure rates decrease significantly with single-modality treatment. Chemoradiation protocols are generally associated with high clinical response rates but limited pathologic responses for large primary tumors. Tumor stage, overall treatment time, overall stage, and the addition of a neck dissection significantly influence locoregional control.

Base of tongue carcinomas can be managed with primary radiotherapy, with neck dissection added for patients with palpable lymph node metastases. Brachytherapy boost (20-30 Gy) to the base of the tongue can be added at the same anesthesia level used for the neck dissection. Patients often require temporary gastrostomy and tracheostomy. In addition, brachytherapy has been advocated for recurrent disease at the primary site.

Surgical therapy

The choice of treatment for base of tongue carcinoma is controversial, with options including surgery alone, radiotherapy alone, or multimodality treatment. Tumors of the tongue base have traditionally been removed by resecting the mandible or by using a translabial transmandibular approach. These procedures involve significant morbidity, including lip and chin scars, malocclusion, compromised deglutition, chronic aspiration, and altered speech articulation. Therefore, alternative techniques have been described to minimize the morbidity associated with transmandibular tongue resection.

As compared to transmandibular resection of tumors, transpharyngeal approaches show no measurable difference in terms of survival, tumor-free margins, speech, or swallowing; furthermore, transpharyngeal approaches result in less aspiration than transmandibular resection.

Many clinicians manage this disease with combined partial glossectomy (with attempts to avoid laryngectomy if possible) with planned postoperative radiotherapy. The risk of aspiration is higher for older patients with large primary tumors, and total laryngectomy is sometimes required.

Good locoregional control rates have been reported at the expense of functional outcome. In general, surgery with radiotherapy is associated with better survival and less locoregional failure but more systemic failure than nonoperative methods of treatment. Positive margins are associated with a higher local failure rate. The placement of permanent gastrostomy tubes and/or the performance of tracheostomy to prevent aspiration are not uncommon. Postoperative radiotherapy is indicated for advanced disease.

Follow-up

Generally, patients are monitored monthly for the first 12-18 months following therapy. Follow-up diagnostic imaging studies are recommended in the first 6 months, particularly in patients who undergo nonsurgical treatment.

For excellent patient education resources, visit eMedicine's Cancer and Tumors Center. Also, see eMedicine's patient education article Cancer of the Mouth and Throat.

COMPLICATIONS

Section 7 of 10  

• Authors and Editors
• Introduction
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Complications of treatment include chronic dysphagia, sepsis, anemia, fistula, osteoradionecrosis, aspiration, and death.

OUTCOME AND PROGNOSIS

Section 8 of 10  

• Authors and Editors
• Introduction
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Treatment results for carcinomas of the base of the tongue are measured in terms of speech and swallowing function; the need for gastrostomy or tracheostomy tubes; local, regional, or distant control; and patient survival and quality of life. Historically, patients with advanced-stage disease have been treated with surgical resection and postoperative radiotherapy. Considering all stages, locoregional control rates approach 70-85% versus 50-75% with stage 4 disease following partial glossectomy, neck dissection, and postoperative radiotherapy. Overall survival rates range from 50-65%, with improved survival with early-stage disease. Even in the presence of advanced-stage disease, the mandible and larynx can be preserved in 80% of patients.

Patients with positive surgical margins are at high risk of locoregional failure and death from disease. Among patients with positive or close margins, postoperative radiotherapy doses of 60 Gy or more achieve excellent long-term local control rates. Complications for this approach include pharyngocutaneous fistula and chronic aspiration. Long-term functional outcome data demonstrate decreasing function with increasing T stage following surgical resection. The prevalence rates of regional and distant failure are approximately 20% and 30%, respectively. The actuarial incidence rate of a second primary malignancy of the upper aerodigestive tract is approximately 35% at 5 years.

In an effort to decrease the alteration in speech and swallowing function associated with extensive surgical resection of the base of the tongue, external radiotherapy alone or in combination with brachytherapy and/or neck dissection has been used as a treatment strategy. The best local control rates at 5 years with external radiotherapy alone are, for T1, 96%; for T2, 91%; for T3, 81%; and for T4, 38%. Similarly, brachytherapy alone is effective for lesions smaller than 4 cm, but extensive lesions have reported local recurrence rates of as high as 50-60%. Improved local control rates approaching 80% can be achieved with the combination of external and implant radiation for T1-3 lesions.

The addition of a planned neck dissection for patients with clinically evident regional lymph node metastases offers statistically significant improved regional control (80-90%) and disease-specific survival. A brachytherapy boost (20-30 Gy) to the base of the tongue can be performed at the same anesthesia level used for the neck dissection with temporary tracheostomy.

The addition of chemotherapy to the management of advanced base of tongue carcinoma is ongoing, and the results from this treatment option are not widely reported in the literature. The 5-year disease-specific and absolute survival rates of 50-65% are comparable to surgical resection. The majority of recurrences are evident within the first 2 years following treatment. Complications of radiotherapy include lost of taste/saliva, tissue necrosis, and osteoradionecrosis of the mandible.

Improved quality-of-life data have been reported from selected patients treated with radiotherapy for carcinoma of the tongue base, although no prospective, randomized, or case-matched controlled studies are available in the literature. Advancing T stage is associated with decreased quality-of-life scores regardless of treatment modality. Of all head and neck subsites, treatment of base of tongue cancer has the greatest impact on speech and swallowing function and on quality of life. The addition of neck dissection to primary radiotherapy for tongue base cancer has no impact on posttreatment quality of life.

FUTURE AND CONTROVERSIES

Section 9 of 10  

• Authors and Editors
• Introduction
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Current management of base of tongue cancer remains controversial because of the variety of techniques available for treatment. Gene therapy and new chemotherapeutic regimens have garnered great interest in an effort to control disease and limit morbidity.

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

• Hanna E, Wanamaker J, Adelstein D, et al. Extranodal lymphomas of the head and neck. A 20-year experience. Arch Otolaryngol Head Neck Surg. Dec 1997;123(12):1318-23. [Medline].
• Harrison LB, Lee HJ, Pfister DG, et al. Long term results of primary radiotherapy with/without neck dissection for squamous cell cancer of the base of tongue. Head Neck. Dec 1998;20(8):668-73. [Medline].
• Horwitz EM, Frazier AJ, Vicini FA, et al. The impact of temporary iodine-125 interstitial implant boost in the primary management of squamous cell carcinoma of the oropharynx. Head Neck. May 1997;19(3):219-26. [Medline].
• Housset M, Baillet F, Dessard-Diana B, et al. A retrospective study of three treatment techniques for T1-T2 base of tongue lesions: surgery plus postoperative radiation, external radiation plus interstitial implantation and external radiation alone. Int J Radiat Oncol Biol Phys. Apr 1987;13(4):511-6. [Medline].
• Machtay M, Perch S, Markiewicz D, et al. Combined surgery and postoperative radiotherapy for carcinoma of the base of radiotherapy for carcinoma of the base of tongue: analysis of treatment outcome and prognostic value of margin status. Head Neck. Sep 1997;19(6):494-9. [Medline].
• Mendenhall WM, Stringer SP, Amdur RJ, et al. Is radiation therapy a preferred alternative to surgery for squamous cell carcinoma of the base of tongue?. J Clin Oncol. Jan 2000;18(1):35-42. [Medline].
• Safa AA, Tran LM, Rege S, et al. The role of positron emission tomography in occult primary head and neck cancers. Cancer J Sci Am. Jul-Aug 1999;5(4):214-8. [Medline].
• Zelefsky MJ, Gaynor J, Kraus D, et al. Long-term subjective functional outcome of surgery plus postoperative radiotheraphy for advanced stage oral cavity and oropharyngeal carcinoma. Am J Surg. Feb 1996;171(2):258-61; discussion 262. [Medline].

Article Last Updated: May 25, 2006