Malignant Tumors of the Base of Tongue Treatment & Management

The choice of treatment for patients with malignant neoplasms of the base of the tongue depends on various 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.^[4] 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 clinical protocols include radiotherapy as a major component of the treatment plan.^[5] 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 present.

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 regardless of treatment. Chemoradiation protocols are generally associated with significant morbidity in terms of speech and swallowing which tend to improve over time. 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 chemoradiotherapy, with elective planned neck dissection for patients with palpable lymph node metastases. Brachytherapy boost (20-30 Gy) to the base of the tongue has been used in the past but has largely been replaced by three dimensional radiotherapy treatment planning. Patients usually require gastrostomy and occasional tracheostomy. The addition of epidermal growth factor receptor (EGFR) inhibitors, including the monoclonal antibody (MAb) cetuximab, has show efficacy in the treatment of primary and recurrent squamous cell carcinomas of the head and neck.

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 with 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. Recent advances in the application of minimally invasive technologies to cancers of the base of tongue have resulted in similar locoregional control rates with the decreased morbidity of larger, open procedures. These advanced surgical techniques require additional training and equipment to be performed but reported results are promising.

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. Planned postoperative chemoradiotherapy is indicated for advanced disease.

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

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 with surgical resection. Most 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.

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.