Fig. 10.1
Squamous cell carcinoma of the oral cavity. a Large ulceration of the gum (between arrowheads) with friable, necrotic surface. Posterior molars are seen to the left of the ulcer. b Infiltrating moderately well-differentiated squamous cell carcinoma with ulcerated surface. c Nests of pleomorphic, moderately differentiated squamous cells with numerous mitoses (arrows), some of them atypical (arrowhead)
Diagnosis and Evaluation
Unfortunately, because of the rarity of these tumors in children, it is not uncommon for patients to come to attention after incomplete resection of what was felt to be a benign lesion. However, such procedures can create greater challenges for local control in the future, and initial resection through tumor is associated with a poorer prognosis [16]. Therefore, whenever possible, initial nasal or oral endoscopy can offer opportunity for biopsy under direct visualization. Careful examination can also help to define the extent of disease. If necessary, the diagnosis can also be made using biopsy of involved cervical lymph nodes in the presence of an identified mucosal lesion.
Imaging studies should include visualization of the primary tumor and nodal areas, including anterior cervical, posterior cervical, and retropharyngeal nodes. Both head and neck magnetic resonance imaging (MRI), for optimal soft tissue involvement, and computed tomography (CT), for evaluation of bony structures and identification of tumor erosion into bones, are indicated. A positron emission tomography (PET) scan should be performed to evaluate for regional and distant disease, and can help to identify involved lymph nodes, although reactive lymph nodes can also be PET positive, so interpretation of results often involves clinical correlation. Finally, evaluation for distant disease at diagnosis should include a chest CT scan for pulmonary metastases.
Squamous cell carcinomas of the head and neck can be classified pathologically according to the Broder classification [17], which relies on differentiation:
G1
well differentiated
G2
moderately well differentiated
G3
poorly differentiated
G4
undifferentiated
Most squamous cell carcinomas are moderately or poorly differentiated (Fig. 10.1b, c); differentiation is not, however, predictive of survival [18, 19]. Pathology should also be evaluated for lymphovascular and perineural invasion as well as extracapsular lymph node spread, which are predictive of outcomes and response to therapy [20].
Staging of squamous cell carcinomas of the head and neck involves the American Joint Committe on Cancer (AJCC) staging system [21], which predicts clinical outcomes and guides therapy. Each anatomic site has a unique staging system based on the extent of the primary tumor, involvement of regional lymph nodes, and distant metastases. We provide here staging for oral cavity cancer as an illustrative example, but staging should always be based on current AJCC staging for the primary site of origin (Tables 10.1 and 10.2) .
Table 10.1
AJCC staging system for oral cavity squamous cell carcinoma
Value | Definition |
|---|---|
Primary tumor (T) | |
T1 | Tumor 2 cm or less in greatest dimension |
T2 | Tumor more than 2 cm but not more than 4 cm in greatest dimension |
T3 | Tumor more than 4 cm in greatest dimension |
T4a | Moderately advanced local disease Lip: Tumor invades through cortical bone, inferior alveolar nerve, floor of mouth, or skin of face, that is, chin or nose Oral cavity: Tumor invades adjacent structures only |
T4b | Very advanced local disease Tumor invades masticator space, pterygoid plates, or skull base, and/or encases internal carotid artery |
Regional lymph nodes (N) | |
N0 | No regional lymph node metastasis |
N1 | Metastasis in a single ipsilateral lymph node, 3 cm or less in greatest dimension |
N2 | Metastasis in a single ipsilateral lymph node, 3–6 cm in greatest dimension; or in multiple ipsilateral lymph nodes, none more than 6 cm in greatest dimension; or in bilateral or contralateral lymph nodes, none more than 6 cm in greatest dimension |
N3 | Metastasis in a lymph node > 6 cm in greatest dimension |
Distant metastasis (M) | |
M0 | No distant metastasis |
M1 | Distant metastasis |
Table 10.2
Summary staging for oral cavity cancer
Stage | T stage | N stage | M stage |
|---|---|---|---|
Stage I | T1 | N0 | M0 |
Stage II | T2 | N0 | M0 |
Stage III | T3 T1-3 | N0 N1 | M0 M0 |
Stage IVA | T4a T1-4a | N0-1 N2 | M0 M0 |
Stage IVB | T1-4a T4b | N3 N0-3 | M0 M0 |
Stage IVC | Any T | Any N | M1 |
In general for squamous cell carcinomas of the head and neck, early-stage cancers are those designated as stages I and II. These tumors are small in size without deep invasion of surrounding structures, and without regional lymph node involvement or distant metastases. Advanced tumors, which are stage III and IV tumors, have significant local invasion, regional lymph nodes, and/or distant metastases. Early-stage and advanced tumors are distinct prognostically and require different treatment modalities.
Treatment
Overview
Because of the rarity of these cancers in children and the consequent lack of clinical trials, treatment is largely based on adult regimens. This is supported by small series demonstrating similar outcomes in pediatric and adult patients with oral and tongue carcinomas [22, 23], although data in the pediatric setting remain quite limited. Special consideration should be taken of the consequences of aggressive surgery and radiation in children.
Approximately one-third of adult patients present with early-stage (stages I and II) squamous cell carcinomas, and aggressive local control confers excellent survival for most early-stage patients. Use of either surgery or radiation, depending on the resectability of the lesion, is usually sufficient. Treatment modality, including choice of radiation or surgery for local control, should be determined for each patient on an individual basis. Thus, careful discussion with a multidisciplinary team including otorhinolaryngology, oncology, and radiation oncology can offer optimal planning for individual patients before local control is attempted. When high-risk features are found at resection, adjuvant radiation or chemoradiation is recommended.
In contrast, patients with advanced (stage III and IV) disease usually require combined modality therapy, including aggressive local control and systemic chemotherapy, although the optimal sequence of these modalities is not known.
Early-Stage Disease
Because both surgery and radiation can offer excellent cancer control, primary considerations include whether surgical local control is possible and whether surgery or radiation will provide a better functional outcome. In the adult setting, surgery is often the modality of choice for early-stage disease at most anatomic sites. Surgery requires wide local excision [24]; positive margins require re-resection or postoperative radiotherapy. Thus, surgical resection should be attempted only for lesions that are deemed to be resectable with wide margins. For lesions that invade the skull base, for example, radiation alone should be considered, because even an aggressive resection is not expected to obviate the need for radiation. Frozen sections may be used intraoperatively to ensure adequacy of surgical margins.
Even in patients with a clinically negative neck, neck dissection should be considered [25]. Evaluation of the neck helps to determine the extent of disease for consideration of adjuvant radiation or chemoradiotherapy. Typically ipsilateral dissection is adequate in the absence of clinical concerns; however, midline lesions such as those in the palate, base of tongue, and supraglottic larynx may require bilateral dissection, given the high risk of bilateral lymphatic drainage. In addition, lesions of the anterior tongue and floor of mouth require evaluation of the submandibular glands. For oral cavity cancers, the depth of invasion predicts nodal involvement; thus, neck dissection should be considered for lesions with a depth of greater than 4 mm [26]. Any clinically involved nodes should be removed, with bilateral dissections for patients with clinically significant bilateral nodes.
Although surgery is the treatment of choice for many patients with resectable limited-stage disease, patients with laryngeal carcinoma benefit from radiation, which offers the prospect of voice preservation [27]. Similarly, radiation may provide the optimal functional outcome for patients with oropharyngeal cancers at the base of tongue or tonsils . Finally, patients with nasal or sinonasal tumors frequently require postoperative radiation, given high rates of local recurrence with resection alone, except in the smallest (T1) lesions .
For children, the balance of risks and benefits of surgery and radiation is complicated by added pediatric toxicity of radiation, which impairs bony growth for children who are not fully mature, and which confers a lifetime second tumor risk that is magnified over the long hoped-for lifetime of these young patients. The use of proton beam radiotherapy has been proposed as one way to mitigate these risks, but it is not widely available, and the extent to which it mitigates these risks is not known.
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