Although lesions of the oral cavity are usually quite visible compared to other head and neck subsites such as the oropharynx, larynx, hypopharynx, and sinonasal tract, a large proportion will present at an advanced local stage. A complete history will elucidate the clinical course. The timing of presentation and relative growth of the primary lesion will alert to rapidly progressive tumors that require urgent intervention before nutritional and airway issues become critical. Similarly, the presence and growth pattern of any clinical neck disease will be informative. Associated symptoms such as otalgia can portend more advanced disease than may be initially noted. Trismus also carries significant implications as it can be a harbinger of deep infiltration into the pterygoid musculature. Oral pain and odynophagia are often early symptoms but indicate advanced disease. Functional issues such as dysphagia and dysarthria may be related to tumor-associated pain or the physical presence of tumor in the oral cavity. Tumors may also involve cranial nerves, V, VII, IX, X, and XII. Weight loss, halitosis, or loose teeth can indicate advanced disease. Dysarthria may be secondary to pain or signal involvement of the hypoglossal nerve. A thorough past medical history should be obtained including current medications (anticoagulants), previous interventions (biopsies, lesion excisions, or aerodigestive malignancy treatments), and medical comorbidities that will be of critical importance for surgical planning (coronary artery disease, chronic obstructive pulmonary disease).

A history of salient risk factors is mandatory not only for assessment of causation but also to begin treatment planning. Smokers should be advised to stop and cessation counseling undertaken. Numerous studies indicate that patients who smoke tobacco during head and neck cancer treatment have significantly worse treatment courses and overall survival compared to those who stop smoking (33). Continued alcohol use and abuse may also have significant negative impact. Alcohol use comorbidities, including cirrhosis and encephalopathy, can seriously affect treatment planning and long-term care. Furthermore, the abrupt cessation of alcohol use, which normally accompanies impatient surgical care, may place patients at significant risk for alcohol withdrawal syndrome and its sequalae (34,35).

Cancers involving the oral cavity are readily assessed by physical examination in the clinic. The overall quality of the tumor should be described: exophytic, ulcerative, pedunculated, etc. A clear demarcation of the specific subsite of the oral cavity affected by the neoplasm is essential: tongue, floor of mouth, etc. As tumor staging in the oral cavity is size based, the dimensions of the lesion need to be clearly defined with particular attention to the demarcation points of 2 and 4 cm. If a lesion extends from one head and neck subsite to another, this too must be noted such as a tongue cancer extending into the floor of mouth. Palpation is essential to determine factors such as depth, degree of infiltration, immobility, and adherence to bone—all of which portend more serious disease. Likewise, palpation of the base of tongue, although unpleasant for the patient, offers critical information.

As the primary risk factors for oral cavity malignancies are also prime risk factors for other upper aerodigestive tract subsites, such as oropharynx and larynx, a complete head and neck physical examination and assessment is required of not only the primary tumor and its associated anatomical extension, but a thorough appraisal of the upper aerodigestive tract to evaluate for second primary tumors. The process of field cancerization—“the development of premalignant clones of cells throughout the aerodigestive tract because of repeated exposure of the tissue to carcinogens in tobacco products” (36)—accounts for the significant rates of second primary tumors in head and neck cancer patients with primary tumors of subsites separate from the second lesion. Mirror exam or fiberoptic examination of all visible upper aerodigestive tract mucosal surfaces should be undertaken as part of the initial clinical evaluation.

Assessment of regional spread is required. The entire neck should be palpated for potential metastatic spread of disease with particular attention paid to the assessment of the lymphatic levels at greatest risk for each specific region of the oral cavity (Table 119.1). Bimanual palpation, with one gloved finger in the mouth and the other palpating the external neck, is beneficial for assessment of the submental and submandibular triangles. Mobility of suspicious nodes should be noted. Fixed adenopathy is a poor prognostic feature and can indicate carotid encasement as well as deep muscle infiltration, factors ultimately affecting resectability.

The appropriate use of imaging for the evaluation of the primary tumor, regional lymph node basins, and chest imaging further augments the comprehensive assessment of oral cavity neoplasms and should be addressed at the earliest clinical time point. If possible, imaging is usually recommended prior to tissue acquisition by biopsy or fine needle aspiration (FNA) to limit any effect these interventions may have on radiologic findings. Plain films currently have little utility in evaluation of oral cavity cancers. With recent technologic advances such as reformatting, image acquisition speed, and low-dose scanning, much greater detail can be obtained with computed tomography (CT) imaging in a similar amount of time with minimal increase in radiation dosage. CT imaging provides excellent bony definition, which is critical in many oral cavity
subsites. When combined with contrast utilization, CT imaging can also provide excellent soft tissue definition. The rapid acquisition time of CT scans is also an important consideration as some patients with advanced oral cavity cancers may not be able to tolerate the positioning and necessity of prolonged immobility required for other imaging techniques.

Magnetic resonance imaging (MRI), with contrast enhancement and use of differential weighting, can provide truly outstanding soft tissue definition and demarcation of tumor involvement. Similarly, evidence of perineural spread and cranial nerve involvement may be obtained with MRI. MRI evaluates mandibular invasion with greater sensitivity than CT, though with less specificity (37). Although delivering no ionizing radiation, MRI does have disadvantages of increased cost, geographic inaccessibility, and longer acquisition times.

As both CT and MRI have specific advantages and disadvantages, choice of imaging modality will be determined by the primary site of the lesion and the specific clinical information desired in the evaluation of the primary site and the regional lymphatics (Figs. 119.8, 119.9, 119.10 and 119.11). Assessment of bone involvement is best evaluated with CT scan and is critical in alveolar ridge, RMT, and hard palate sites. The RMT can be particularly challenging to assess, and studies demonstrate that bone invasion may not be notable on preoperative CT imaging in one-quarter of patients evaluated (38). Bone involvement by tumors originating in soft tissue sites such as tongue and floor of mouth has significant impact on treatment planning. Specifically, the evaluation of mandibular involvement is important in primary tumor staging and surgical planning. Again, high-resolution CT scanning is the current imaging modality of choice, although recent studies indicate the increasing utility of MRI, especially for marrow and nerve involvement. The
use of CT scanning has been shown to be helpful in clinical evaluation of the primary tongue tumors (39). Due to the well-established fascial planes surrounding the lingual artery and hypoglossal nerve, a CT scan will aid in the surgical evaluation for a partial glossectomy, as the surgeon evaluates the ability to save the neurovascular bundle on one side of the tongue. This has been greatly aided by high-quality reformatting allowing assessment of the coronal, sagittal, and axial planes. Yet, MRI provides superior definition of tumor extent and involvement in soft tissue areas such as the tongue, floor of mouth, and buccal region and should be considered for these lesions. Patients with clinical evidence of neural involvement and with tumors predisposed to perineural involvement, such as floor of mouth adenoid cystic carcinomas or palatal or alveolar ridge carcinomas, can also benefit from MRI to assess potential proximal neural involvement.

In the United States, CT and MRI are the most commonly used imaging modalities to evaluate for regional metastasis, though with somewhat limited accuracy (40). Definition of clinical evident adenopathy is straightforward with attention focused on overall size, multifocality, evidence of extracapsular spread, deep muscle involvement, carotid involvement, and skull base involvement. The clinically negative neck provides a greater challenge. Criteria for positivity can vary but often include size greater than 10 mm, evidence of central necrosis, loss of ovoid shape, loss of fatty hilum, and the presence of extracapsular extension (41). Though not widely used in the United States, ultrasound has been shown to be more accurate in the assessment of metastatic lymph nodes, specifically in assessing the integrity of the hilar architecture and blood flow in benign appearing lymph nodes (42). In the evaluation of the combination of selective ultrasound-guided FNA biopsy, several European studies indicate the usefulness of these techniques for assessment of the occult metastatic neck disease (43,44,45).

The role of positron emission tomography (PET) scans in the staging of oral cavity cancer has not yet been defined. The combination of the PET imaging with CT scanning to provide PET/CT modality has increased the applicability of this imaging technique, yet limitations remain. The CT images obtained with combined PET/CT are often not of the detail and quality obtained with dedicated high-resolution, contrast-enhanced CT scans and therefore should not be considered a replacement. PET imaging offers little added information over standard imaging for assessment of primary lesions. In the assessment of regional disease, PET is often confirmatory, not enlightening. PET also demonstrates limitations in the assessment of the clinical negative neck especially for nodes less than 1 cm. Despite equivocal evidence, PET/CT scans are often obtained in the preoperative setting. Although PET/CT may be of limited use in management of the primary disease, it can aid in the detection of distant metastatic disease (46). Therefore, patients at high risk for metastatic disease such as those with recurrent disease, large primary site tumors, extensive and low neck adenopathy, as well as patients requiring surgical intervention with significant potential morbidity should be considered for evaluation of potential distant metastatic disease with PET/CT. Thus, although of limited utility in the evaluation of the primary disease (47), the more significant role of PET/CT imaging may be in posttreatment assessment in distinguishing posttreatment effect from neoplasm in cases of recurrence or persistent tumors (48).

Pulmonary metastasis is the most common site of distant disease spread in oral cavity, and formal evaluation of the chest is mandatory. Furthermore, widespread tobacco use by patients with oral cavity cancer predisposes this risk group to increased rates of synchronous primary lung cancers. For patients at low risk for distant spread or primary lung cancer, chest x-ray (CXR) is sufficient for evaluation of the chest. If there is greater concern for pulmonary metastasis because of risk factors noted above, excessive tobacco use, or suspicious chest plain film, then chest CT is indicated. When clinical circumstances warrant it, PET/CT imaging may be alternatively employed.

Comprehensive staging of the oral cavity tumors performed in the clinic setting requires tissue for diagnosis. As the oral cavity subsites are quite accessible in the office exam, a biopsy of the primary site can readily be obtained with minimal issue under local anesthesia. This can be completed with an incisional technique or cup forceps.

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