Small tumors at certain sites, such as the crypts of the tonsils, the glossotonsillar sulci and the tongue base rarely produce symptoms and are not always easy to detect. When present, the initial symptoms of oropharyngeal cancer are often vague and nonspecific, leading to a delay in diagnosis. Consequently, the overwhelming majority of patients present with locally advanced tumors.
Presenting symptoms may include sore throat, foreign-body sensation in the throat, altered voice or referred pain to the ear that is mediated through the glossopharyngeal and vagus nerves. Over two-thirds of patients present with a neck lump. As the tumor grows and infiltrates locally, it may cause progressive impairment of tongue movement which affects speech and swallowing, and necrosis and secondary infection may result in foul breath or even hemorrhage.
All patients must undergo a complete and thorough clinical examination of the upper aerodigestive tract and the neck, including fiberoptic nasolaryn-goscopy. Most aspects of the pharynx and larynx can be readily assessed in the office with a flexible endoscope under topical anesthetic, but areas such as the pharyngoglossoepiglottic folds and the posterior surface of the soft palate may be difficult. The visual extent of the tumor is often misleading, and accurate assessment must include bimanual palpation of the tumor. Particular note must be taken of the inferior limit and circumferential extent of the tumor, its superior extent towards the nasopharynx, and mobility of structures at or below the level of the hyoid. Advanced tumors that cause trismus may be better assessed under a general anesthetic. Morphologically, a squamous cell carcinoma may present either as an exophytic (Figure 6-3) or ulcerative (Figure 6-4) lesion. Tumors of the minor salivary glands may present as smooth, lobulated swellings without surface ulceration (Figure 6-5), and malignant lymphomas typically cause nodular enlargements in the tonsil or tongue base.
Direct involvement of the XIIth nerve with the tumor, or infiltration from a metastatic neck node results in paralysis that is manifested by wasting of the ipsilateral tongue with deviation to that side on protrusion. Involvement of the glossopharyngeal and vagus nerves near the skull base must be suspected when there is impaired movement of the soft palate and ipsilateral vocal cord paralysis respectively. Similarly, involvement of the inferior alveolar nerve (impaired sensation over the anterior chin which is the sensory distribution of the mental nerve) and the lingual nerve in the infratemporal fossa (altered sensations over the lateral part of the tongue) are ominous signs that indicate locoregionally advanced disease.
Fine-needle aspiration cytology (FNAC) of any suspicious node in the neck at the initial consultation
generally allows the clinician to establish tissue diagnosis in patients in whom the primary tumor is not readily visible. Occasionally, aspiration of cystic fluid from a necrotic metastatic node may give a false-negative result. The false-negative rate can be reduced somewhat by completely removing cyst fluid and repeating FNA of any residual solid mass. A complete and detailed head and neck exam must
be complemented by appropriate imaging studies in these cases to rule out an obvious mucosal primary lesion before an open biopsy of a suspicious neck node is attempted.
Apart from the obvious advantages of CT and MRI in detection of subclinical nodal disease, imaging can also provide other information that may be vital to treatment planning. The controversy about the superiority of one imaging modality over the other seems unwarranted because both CT and MRI have their specific advantages, and may be used to complement each other based on the specific information required for making accurate treatment decisions. As a general rule, MRI enables superior distinction of tumor from muscle and other soft tissue while CT is better at imaging cortical bone. Gadolinium-enhanced MRI has also been shown to reliably demonstrate invasion along nerves. Both CT and MRI are effective in evaluating neck metastases, but accurate prediction of invasion of structures such as the carotid sheath and prevertebral fascia is usually not possible until direct assessment at surgery. Imaging may identify retropha-ryngeal nodes that are ordinarily out of bounds to palpation. Imaging is also especially valuable in assessing the neck in obese patients or those with a thick neck. Assessment of the post-radiotherapy or postsurgical neck is unreliable because differentiation between
tumor, edema, inflammation and fibrosis is difficult. 18FDG-PET scanning5 may be the most sensitive technique currently available for these situations. The role of imaging in the detection of early mandibular invasion remains questionable, and a meticulous evaluation under anesthetic has been shown to be more reliable in assessing bony involvement.6 A preoperative Panorex (orthopantomogram) may be necessary to assess the state of the dentition prior to instituting radiotherapy. Radiologic imaging, however, is essential to treatment planning if a mandibulotomy or any form of mandibular resection is planned. Dynamic contrast imaging using videofluoroscopy provides vital information on the functional aspects of deglutition and protection of the airway, both pre- and post-operatively. It is also a useful aid for prescribing speech and swallowing exercises. A plain radiograph of the chest helps screen for metastatic carcinoma, synchronous bronchial primary and coexisting acute or chronic pulmonary disease. Further investigation with chest CT scan, pulmonary function tests or bron-choscopy is generally merited based only on the patient's symptoms or an abnormal chest film.
A detailed examination and biopsy under general anesthetic may be the only accurate method of assessing the extent of tumors such as those of the tongue base that may be in a submucosal location. It may be prudent to use this opportunity to carry out dental extractions in patients with poor dentition who will require radiation therapy in order to minimize delay in treatment. The information collected by clinical, endoscopic and radiologic examination is then collated and used to assign a TNM stage to each individual tumor.
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