Transoral Robotic Surgery for Neoplasms of the Base of Tongue

Carcinoma of the base of the tongue can be managed with either surgical or nonsurgical approaches. Historically, most surgical resections in this region have involved open approaches, such as suprahyoid pharyngotomy or lip-split mandibulotomy. Given the morbidity of these approaches, organ preservation protocols initially developed for cancer of the larynx were adapted to the oropharynx. However, primary chemoradiation is not without serious toxicity. Long-term treatment-related sequelae from chemoradiation, particularly pertaining to swallowing dysfunction, have become increasingly recognized over time. Transoral robotic surgery (TORS) was developed as a minimally invasive approach through a natural orifice to allow for precision oncologic resections while preserving function.

A major advantage of a primary surgical approach to neoplasms of the base of the tongue is that it provides a pathologic specimen. Accurate staging and assessment of histologic risk factors can thus be definitively determined, rather than relying on imaging alone. With comprehensive pathologic staging, patients can then be risk stratified to receive appropriate adjuvant therapy, if indicated.

Two of the most challenging aspects of the procedure are appropriate patient selection and maximizing exposure during the resection.

Key Operative Learning Points

1.
Appropriate docking and setup of the surgical robot, along with proper selection and then positioning of the retractor, are the keys to optimizing exposure.
2.
The dorsal lingual branch of the lingual artery is typically encountered in the lateral aspect of the resection and must be managed appropriately to prevent postoperative hemorrhage.
3.
The bedside assistant plays a crucial role in the success of the procedure. Appropriate suctioning, traction, and countertraction greatly facilitate surgical access and visualization.

Preoperative Period

History

1.
History of present illness
- a.
  Age of the patient
- b.
  Elicitation of symptoms including dysphagia, otalgia, odynophagia, aspiration, weight loss, and dyspnea. Symptoms can help to guide whether or not a patient is a candidate for TORS.
  - 1)
    Pre-existing dysphagia and/or gross aspiration may indicate the need for prolonged enteral feeding. In addition, these symptoms may suggest deep submucosal infiltration of the cancer that may not be clinically apparent.
  - 2)
    Referred pain such as otalgia may suggest extensive perineural invasion or involvement of the epiglottis.
2.
Past medical history
- a.
  History of prior radiation therapy. Although salvage TORS has been described in the literature, the normal interface between tissue and tumor is often obliterated in these patients and may preclude a minimally invasive resection. In addition, wound healing and vascularity are compromised, and these patients may take many months to heal by secondary intention.
- b.
  Cardiopulmonary fitness and bleeding disorders need to be assessed. Patients with severe cardiac or pulmonary disease may not be able to tolerate major surgery and postoperative rehabilitation. These patients may be better suited for primary chemoradiation. Likewise, patients with known hereditary coagulopathies are predisposed to postoperative bleeding. Given the open wound and healing by secondary intention inherent to TORS, these patients may not be appropriate surgical candidates.
3.
Past surgical history
- a.
  Prior surgical intervention or biopsies for cancer
- b.
  Prior surgery on cervical spine or temporomandibular joint
4.
Family history
- a.
  Bleeding disorders or adverse reaction to anesthesia
5.
Social history
- a.
  Smoking and extensive use of alcohol
6.
Medications
- a.
  Anticoagulants including Coumadin, Plavix, and aspirin should be discontinued preoperatively and ideally for at least 2 weeks after surgery. It should be recognized that the use of supplements such as Ginkgo biloba, fish oil, and vitamin E may pose an increased risk for postoperative bleeding.
- b.
  Long-term use of steroids may inhibit wound healing by secondary intention.

Physical Examination

1.
Evaluation of the base of the tongue is performed by both direct examination and flexible laryngoscopy. The glossotonsillar sulcus, vallecula, and epiglottis are assessed for grossly visible cancer. Extension of the cancer to the midline is also assessed. Palpation, if tolerated, is critical to estimate depth of invasion into the tongue.
2.
Palpation of the neck is performed. Care is taken to note the number of lymph node metastases and whether obvious contralateral metastasis is present. Lack of mobility of the lymph nodes may imply extracapsular extension.
3.
Oral aperture along with mandibular dimensions and positioning, tongue size and shape, and dentition are evaluated to determine if sufficient transoral exposure is possible.

Imaging

1.
Magnetic resonance imaging (MRI) or computed tomography (CT) is performed to evaluate lymph node status, presence or absence of gross extracapsular extension, and extent of tumor invasion. Obvious involvement of deep parapharyngeal space structures, extrinsic tongue musculature, and the hyoid bone may preclude transoral resection. Sagittal sections are helpful in defining anterior extension of the cancer. From our evolving experience with imaging and TORS, it appears that MRI may be the best imaging study to provide more detail with respect to depth of invasion into both intrinsic and extrinsic tongue musculature.
2.
Positron emission tomography–CT–computed tomography (PET-CT) is typically performed for initial staging and metastatic evaluation.

Indications

1.
TORS can be performed for all tumors of the base of the tongue that are deemed resectable from a transoral approach. However, the ideal candidates are those who are anticipated from preoperative evaluation to be able to avoid either adjuvant chemotherapy or concurrent chemoradiation, as well as maintaining articulation and swallowing function.

Contraindications

1.
Deep involvement of more than one-half of the base of the tongue. These patients are at risk for significant functional deficits after resection or risk of devascularizing the tongue from bilateral lingual artery sacrifice.
2.
Invasion of the skull base, hyoid bone, great vessels, or mandible
3.
Deep involvement of the extrinsic tongue musculature
4.
Large cancers of the glossotonsillar sulcus that risk exposure of the carotid artery

Preoperative Preparation

1.
If exposure or resectability is indeterminate, patients should be brought to the operating room for an initial staging direct laryngoscopy with examination under anesthesia. The FK-WO retractor can be used at this time to determine if adequate exposure can be obtained.
2.
Neck dissection can be performed either concurrently or in a staged fashion. Our protocol is to perform a staged surgery with the neck dissections done before the TORS resection. The lingual artery, facial artery, and the superior laryngeal artery are ligated during the neck dissection as a prophylaxis against potential catastrophic postoperative hemorrhage. This staged neck dissection approach also minimizes edema of the tongue and airway and prevents potential pharyngocutaneous fistula if extensive resection of the glossotonsillar sulcus is anticipated.

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Introduction