| Carcinoma of the
Nasopharynx Carcinoma of the nasopharynx is uncommon in the United States. Among H&N cancers, it has the highest propensity to metastasize to distant sites. Nasopharyngeal cancer also poses a significant risk for isolated local recurrences after definitive irradiation for locally advanced disease. Oddly enough, regional recurrences are uncommon in this disease, occurring in only 10% to 19% of patients. The NCCN clinical practice guidelines for the evaluation and management of carcinoma of the nasopharynx attempt to address both local and distant disease risk. Radiation therapy was the standard treatment for all stages of this disease until the mid-1990s when trial data showed improved survival for locally advanced tumors treated with concurrent RT and cisplatin.. Stage is accepted as prognostically important. The prognostic significance of histology is still controversial. Several retrospective reviews indicated local control and survival appear to depend on histologic subtypes, whereas one study found no association between histology and these outcomes. The World Health Organization (WHO) classification for nasopharyngeal cancer is used most often. Type 1 represents well to moderately well differentiated squamous cell cancers. Type 2 denotes nonkeratinizing tumors, including transitional carcinoma and lymphoepithelioma. Type 3 represents undifferentiated carcinomas, including lymphoepithelioma, anaplastic, clear cell, and spindle cell variants. Workup and Staging In addition to a
history, physical examination, and nasopharyngeal examination and biopsy, the workup of
nasopharyngeal cancer includes dental evaluation and appropriate diagnostic imaging
studies (eg, CT scan or MRI). These studies are important to determine the full extent of
tumor in order to assign stage appropriately and to design radiation ports that will
encompass all the disease with appropriate doses. A chest x-ray should also be obtained.
Multidisciplinary consultation is encouraged. The 2002 AJCC staging classification is used
as the basis for treatment recommendations. Treatment options are subdivided according to T, N, and M status, rather than by stage alone. Patients with early-stage nasopharyngeal tumors (T1, N0, M0, and selected T2 tumors) may be treated with definitive RT to the nasopharynx, with elective radiation to the neck. The local control rate for these tumors ranges from 80% to 90%, whereas T3-4 tumors have a control rate of 30% to 65%. Trials using three-dimensional RT planning are ongoing at the institutional level, but, thus far, no definite gains have been noted using radiation alone in T3-4 cancers. The combination of RT and platinum-based chemotherapy has been shown to increase the local control rate from 54% to 78%. The intergroup trial 0099, which randomly assigned patients to chemotherapy plus external beam RT versus external radiation alone, closed early when an interim analysis disclosed a significant survival and progression-free survival advantage favoring the combined chemotherapy and radiation group.The addition of chemotherapy also decreased local, regional, and distant recurrence rates. The question of which subsets of patients with stage III and stage IV tumors may respond equally well to appropriate doses of radiation remains unanswered at present. Until other data can provide more clarity, the guidelines recommend combined chemotherapy plus radiotherapy for T2-4 lesions and for T1 lesions with positive nodes.The scheduling and doses of chemotherapy are those used in the intergroup trial. Although an unusual occurrence, a patient with a neck node unresponsive to combined therapy should be considered for a neck dissection. Initial therapy for patients who present with metastatic disease should consist of a platinum-based combination chemotherapy regimen. If a complete response is achieved, definitive RT should be administered to the primary tumor and neck area. For early-stage cancer, radiation doses of at least 70 Gy given with standard fractions are necessary for control of gross tumor Intracavitary brachytherapy has proven to be efficacious as a boost to gross disease in larger T1-2 tumors.. The recommended follow-up for patients with treated cancers of the nasopharynx includes periodic physical examination and an assessment of thyroid function (ie, the TSH level should be determined every 6 to 12 months). Increased TSH levels have been detected in 20% to 25% of patients who received neck irradiation. |