Malignant Tumors of the Base of Tongue Treatment & Management

Updated: Apr 05, 2021
  • Author: Rishi Sethia, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Treatment

Medical Therapy

Treatment for patients with malignant neoplasms of the base of tongue depends on various factors. These include the pathology, histology, and immunohistochemical staining results (p16 status in SCC); the clinical stage of the neoplasm; the patient's age and associated medical conditions; patient compliance; potential adverse effects or complications; and expected outcomes. In order to allow the patient to make a reasonable and informed decision regarding treatment options, these factors must be discussed in detail before therapy.

As is true with other sites of the head and neck, early stage base of tongue SCC can be addressed via surgical treatment and/or radiation therapy (RT). Advanced-stage tumors may be treated surgically with adjuvant RT/adjuvant concurrent chemoradiation therapy (CRT) or with definitive CRT. The typical regimen for the early and advanced-stage lesions involves 6 weeks of RT and includes a platinum-based chemotherapy agent. More recently, there have been questions regarding the efficacy of using an epidermal growth factor receptor (EGFR) inhibitor, such as the monoclonal antibody agent cetuximab, in this setting. [26, 27]

In appropriately selected patients, CRT provides an effective treatment option and obviates the need for surgical intervention. However, RT and CRT can induce toxicity and significantly alter quality of life (QOL), as patients may experience xerostomia, mucositis, speech issues, dysphagia, aspiration, or respiratory distress requiring gastrostomy or tracheostomy placement. [28]  Concurrent CRT with brachytherapy has also been reported for base of tongue SCC, although limited evidence exists to support this treatment option outside of selected patients. [29]  Several trials examining treatment de-escalation and alteration of CRT regimens for HPV-associated oropharyngeal SCC are ongoing in an effort to minimize morbidities. [30]

Immunotherapy treatments with immune checkpoint inhibitors such as pembrolizumab and nivolumab are being investigated in numerous trials but are currently mostly reserved for palliative use in refractory oropharyngeal SCC. As the knowledge surrounding these treatments continues to evolve, immunotherapy could play a promising role in the management of oropharyngeal SCC. [31, 32]

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Surgical Therapy

Surgical excision is based on initial staging, pathology, tumor location, and patient preference. The patient's overall health and ability to tolerate prolonged intraoperative anesthesia must also be taken into account. Depending on the tumor location, anticipated type of surgical resection and reconstruction, and potential need for adjuvant therapy, patients may require a temporary feeding tube and/or tracheostomy tube in order to maintain adequate nutrition and protect the airway, respectively. However, tumors may be considered unresectable because of their size/location, the extent of disease, or tumor invasion into critical structures. All of these factors must be considered when selecting an appropriate, definitive surgical therapy, medical therapy, or palliative management.

Non-SCCs in the form of malignant, solid tumor neoplasms of the base of tongue typically require a surgical approach. With hematologic malignancies like lymphoma, surgery only serves as a diagnostic modality; once a diagnosis is made, nonsurgical treatments (chemotherapy and/or radiation) are employed. SCC, on the other hand, requires a more thorough and thoughtful approach with regard to the appropriate treatment modality for each individual patient. Surgery, when elected, can be performed as the primary modality, with adjuvant therapy, or in the salvage setting with recurrent or persistent disease.

Depending on the size and location of the tumor, various surgical approaches can be applied. Traditionally, a translabial, transmandibular approach was used to remove malignant base of tongue tumors. Such surgery, however, involves significant morbidity, including lip and chin scars, malocclusion, compromised deglutition, chronic aspiration, altered speech articulation, and higher risk for delayed osteoradionecrosis of the mandible. Therefore, alternative techniques have been described, including transoral robotic surgery (TORS) and transoral laser microsurgery (TLM). These minimally invasive approaches have yielded favorable oncologic outcomes while decreasing the morbidity associated with traditional resection approaches. [33, 34, 35, 36, 37]  Numerous studies have supported improved QOL outcomes for TORS and TLM, especially in selected patients who undergo surgery alone. [38, 39, 40]

In patients with inadequate transoral access due to tumor location or difficult anatomy, lateral or transhyoid pharyngotomy may be required, in an open approach that avoids mandibulotomy.

Finally, in extensive lesions not amenable to the aforementioned approaches and in patients having recurrent or persistent disease after radiation or chemoradiation therapy, mandibular split is performed to provide wide access for surgical ablation, as well as reconstruction with vascularized tissue. In patients with large oropharyngeal defects, free flap reconstruction using microvascular anastomosis is the reconstruction method of choice. Typically, radial forearm or anterolateral thigh fasciocutaneous flaps are employed in this setting.

Given the proximity to midline of malignant tumors of the tongue base and the bilateral lymphatic drainage patterns, one must always treat both sides of the neck. With surgery, this typically involves performing bilateral neck dissections for locoregional disease control and accurate pathologic staging analysis. The risk of occult lymph node metastasis from the base of tongue is higher than from other oropharyngeal subsites, ranging from 21-45%. [41]  Thus, elective bilateral neck dissection is often performed with definitive surgical extirpation.

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Follow-up

Although time intervals may vary by institution, patients with oropharyngeal cancer should undergo posttreatment surveillance for the first 5 years. Patients can be monitored beyond this time period depending on patient and clinician preferences; such continued monitoring can be especially important in high-risk patients such as those who continue to use tobacco. For example, patients can be monitored every 3 months for the first year, every 3-4 months for the second year, every 6 months for the third year, every 8 months for the fourth year, and yearly or as needed for the fifth year and beyond. PET/CT scanning is the most sensitive and specific imaging modality for posttreatment surveillance; imaging obtained between 3 and 6 months and 12 months after treatment has important prognostic implications. The likelihood of future recurrence is extremely low following two consecutive negative PET/CT-scan studies between 3 and 6 months posttreatment. [21]

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Outcome and Prognosis

Although malignant tumors of the base of tongue have traditionally held a poor prognosis, there has been a sharp increase in HPV-positive oropharyngeal SCC in recent years, [4] and these patients have notably shown improved survival compared with patients with the HPV-negative form of the disease. One study reported 95% versus 62% 2-year overall survival rates in HPV-positive versus -negative patients, respectively, [42, 2]  with HPV-positive patients appearing to have improved treatment response rates compared with HPV-negative patients (84% vs 57%, respectively, after CRT). [42]  As the number of HPV-associated oropharyngeal SCC cases continues to rise, outcomes will continue to shift as research leads to more advanced understanding of and management strategies for these uniquely treatable malignant tumors.

In addition to epidemiologic contributions to improved outcomes, advances in technology and minimally invasive treatment options have reduced postoperative morbidity and improved prognosis. Numerous studies have demonstrated excellent oncologic outcomes with TLM and TORS, with functional and QOL benefits demonstrated. Grant et al revealed 2-year survival of 92% and 91% for T1 and T2 base of tongue SCCs treated with TLM, with high local control rates. [37]  De Almeida et al reviewed outcomes of 364 oropharyngeal SCC patients who underwent TORS and reported 2-year locoregional control, disease-specific survival, and overall survival rates of 92%, 94.5%, and 91%, respectively. [43]

Brachytherapy serves as a potential adjunct to treatment of base of tongue tumors, with one study revealing a 3-year overall survival rate of 80.9%, a locoregional control rate of 79.9%, and a disease-specific survival rate of 69.5%, when the therapy is combined with CRT. [29]

Adverse pathologic features such as positive margins, ECE, perineural invasion, lymphovascular invasion, and positive lymph nodes yield a worse prognosis and promote the use of adjuvant therapy to improve oncologic outcomes. [44, 45]

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Future and Controversies

Multidisciplinary involvement is critical for appropriate evaluation and management of malignant tumors of the base of tongue. Clinicians are continually investigating how to minimize posttreatment functional deficits and QOL impairment while maintaining favorable oncologic outcomes. The expanded role of minimally invasive surgical modalities such as TORS/TLM, investigation into treatment de-escalation for HPV-associated tumors, and the emerging knowledge surrounding immunotherapy present exciting opportunities for the future.

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Prevention

Although data is still emerging, HPV vaccination provides a unique opportunity to limit the recent surge in HPV-associated oropharyngeal SCC. Guidelines are expanding, and health officials are calling for early and widespread vaccination as a promising, feasible intervention to prevent HPV-associated oropharyngeal SCC. [46]

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