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The most favorable management of oropharyngeal cancer is still controversial. In the past, oropharyngeal cancers were treated with surgery followed by radiation. Surgical resection usually required mandibulectomy or mandibulotomy and removal of pharyngeal musculature, which resulted in significant morbidity. Because of the functional and cosmetic impairments and current development of organ preservation regimens, chemoradiation has become the treatment of choice in many patients with cancer of the oropharynx. Furthermore, studies have demonstrated an increased incidence of human papilloma virus (HPV)-related cancer of the oropharynx, particularly among young adults who have a better prognosis. There are emerging data that less aggressive treatment can be performed in this group of patients without sacrificing the good cure rate.
The oropharynx is the middle part of the throat that extends from the junction of the soft and hard palate superiorly to the superior edge of the epiglottis and the hyoid bone inferiorly, circumvallate papillae of the tongue anteriorly, and pharyngeal wall posteriorly. It includes the base of the tongue, the soft palate, the lateral and posterior pharyngeal walls, the tonsils, and tonsil pillars. The function of this region is crucial in swallowing, respiration, and speech. It is noteworthy that the swallowing function is adversely affected both by surgical resections and chemoradiation. Dysphagia and poor speaking may result in social problems, but aspiration may cause life-threatening complications. Therefore appropriate selection of the type of surgical approach is quite important in the management of cancer of the oropharynx.
The prognosis and treatment of cancer of the oropharynx are strongly related to the involvement of cervical lymph nodes. The incidence of lymphatic metastasis is relatively high, depending on the subsite. Even in patients with no adenopathy at the time of diagnosis, elective ipsilateral or bilateral neck treatment is required either through a neck dissection or by radiation therapy. In addition, the tonsillar fossa and base of the tongue are known as the most common potential mucosal sites in unknown primaries. There is also a risk for metastasis to the retropharyngeal lymph nodes in cancer of oropharynx, particularly in those patients in whom the posterior pharyngeal wall or the soft palate is involved. These nodes are beyond the classical neck dissection. The majority of those patients are required to have adjuvant radiotherapy. In such instances, radiation therapy is rational as a single treatment modality for primary and lymphatic metastasis, as well. Otherwise, transoral surgery is a feasible option in selected early limited cancer, in which the need for adequate exposure is fundamental.
Transoral resection of cancer of the oropharynx was first described by Huet in 1951. This technique eliminates the morbidity created by the mandibular swing or composite resection. In addition, this minimally invasive surgery may avoid adverse consequences of chemoradiation with comparable outcome. Moreover, it provides pathologic staging for further adjuvant treatment. Transoral surgery is generally indicated in early-stage cancer of the oropharynx. This can be done either via transoral robotic surgery or endoscopy-based transoral laser microsurgery. The transoral approach has been expanded with the development of transoral robotic surgery. This technological improvement provides three-dimensional visualization for precise dissection and safety of margins. There are some advantages of robotic surgery, including shorter hospitalization, rapid functional recovery, avoidance of tracheostomy, and reduced need for nasogastric tube feeding. We favor transoral robotic surgery in carefully selected patients.
Careful patient selection
Accurate assessment of tumor extension and lymph node involvement
Surgical anatomy of the carotid artery and association pharyngeal structures
Special training for robotic surgery if transoral robotic surgery is preferred
Ipsilateral or bilateral neck dissection is necessary. It can be done either simultaneously or separately. We prefer concurrent neck dissection following transoral resection.
History of present illness
Persistent sore throat, throat discomfort
Neck mass
Odynophagia, referred otalgia with swallowing, globus sensation
Trismus, dysphagia, bleeding, difficulty moving the tongue
Past medical history
Tobacco use, alcohol consumption, betel quid chewing
HPV exposure
Radiation exposure
Comorbid diseases, including systemic diseases and hemorrhagic diatheses
Medications and herbal products being used
Oral cavity—oropharynx
Must include all mucosal surfaces to evaluate a second primary or extension of the primary tumor to surrounding structures
Any dentures should be removed during the inspection.
Palpation for size, deep fixation, and mobility of the lesion
Assessment of cranial nerves, particularly cranial nerve IX, X, and XII
Endoscopy
Both flexible and rigid endoscopic evaluation
Endoscopy under general anesthesia. This is preferred before definitive treatment in order to evaluate for the adequate exposure and availability of the tumor for transoral approach.
Neck
Palpation of the both necks
Recording of the levels of lymph node involvement
Computed tomography (CT), for bony invasion of the skull base, mandible, and status of the lymph nodes, particularly retropharyngeal lymph nodes
Magnetic resonance imaging (MRI) for the depth of tumor invasion, perineural infiltration, and association with vital structures, particularly the carotid artery
Positron emission tomography–computed tomography (PET-CT) to discover distant metastasis, especially in cases of advanced cancer. Not required in all cases
Primary or recurrent cancer of the oropharynx, which can be excised transorally depending on the surgeons’ experience and patients’ condition and wishes
Generally indicated in T1 and T2 cancers of the soft palate ( Fig. 33.1 ), posterior pharyngeal wall, tonsil and anterior pillar, the base of the tongue, and uvula ( Fig. 33.2 )
Trismus
Inadequate exposure
In robotic surgery, cancer requiring resection of more than 50% of the base of the tongue or more than 50% of the posterior pharyngeal wall ( Fig. 33.3 )
Close association of the tumor with carotid artery
Invasion into the parapharyngeal space
Bone invasion
Tumor fixation of prevertebral fascia
Invasion of the vital structures by the primary cancer
Unresectable lymph node metastasis regardless of the primary cancer
Poor exposure due to patients anatomic situation, such as micrognathia, cervical spine injury, macroglossia
Inability to convert to open surgery intraoperatively
Patients preference for another treatment modality
Comorbid diseases with increased risk for general anesthesia
Distant metastasis. Adenoid cystic carcinoma with limited pulmonary metastasis may be an exception.
Biopsy to confirm the diagnosis
Review any biopsies or tissue from previous surgery
Routine laboratory tests and preparation of red blood cell suspension for probability of transfusion during surgery
Cessation of antiplatelets/anticoagulant drugs
Evaluation of the patient’s dentition is essential to prevent osteoradionecrosis due to probable postoperative radiotherapy.
Dental consultation with prosthodontist for temporary postoperative palatal prosthesis in patients who need partial resection of the palate
Counseling of the patient about the probable needs for temporary tracheostomy and/or nasogastric tube
Cervical lymph node dissection is a part of the treatment of cancer of the oropharynx even in N0 neck; thus the patient should be informed about neck dissection.
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