In a study comparing US to CECT for the staging of hypopharyngeal cancer, US failed to detect significant findings seen on CT in 22.5% of cases, although US proved accurate in diagnosing cartilage invasion and vocal cord immobility [70]. Conversely, US was found to approach the accuracy of CECT and MRI in the evaluation of larynx primary site with 80% to 83.3% accuracy in delineating the correct T stage versus 88.8% for CECT and 76.7% for MRI [71-73]. Variant 2: Suspected or diagnosed nasopharynx cancer or EBV-associated unknown primary of the head and neck. Initial staging. Nasopharyngeal carcinoma (NPC) is a relatively rare cancer with a worldwide incidence of 0.5 to 1.0/100,00 per year [74], with higher endemic rates in Southeast Asian countries. NPC arising from the nasopharyngeal epithelium represents at least 70% of tumors of the nasopharynx and, for this reason, will be the focus of the upcoming discussion [74]. Other histologies, including nasopharyngeal lymphoma, constitute a minority of nasopharyngeal malignancies and will therefore not be emphasized in this section. The World Health Organization classifies Assessment of Head and Neck Cancer squamous cell carcinoma of the nasopharynx based on histopathologic features into keratinizing squamous cell carcinoma, nonkeratinizing squamous cell carcinoma, which is further subdivided into differentiated and undifferentiated type, and basaloid squamous cell carcinoma. Alcohol and smoking are associated with NPC, with the strongest link to keratinizing squamous cell carcinoma, which carries the worst prognosis [75]. Almost all nonkeratinizing squamous cell carcinoma and basaloid squamous cell carcinomas are associated with EBV infection with a slightly weaker association of EBV to keratinizing squamous cell carcinoma [18]. The undifferentiated subtype is most common in endemic areas, representing as many as 93% of all cases [75].
Staging and Post Therapy Assessment of Head and Neck Cancer. In a study comparing US to CECT for the staging of hypopharyngeal cancer, US failed to detect significant findings seen on CT in 22.5% of cases, although US proved accurate in diagnosing cartilage invasion and vocal cord immobility [70]. Conversely, US was found to approach the accuracy of CECT and MRI in the evaluation of larynx primary site with 80% to 83.3% accuracy in delineating the correct T stage versus 88.8% for CECT and 76.7% for MRI [71-73]. Variant 2: Suspected or diagnosed nasopharynx cancer or EBV-associated unknown primary of the head and neck. Initial staging. Nasopharyngeal carcinoma (NPC) is a relatively rare cancer with a worldwide incidence of 0.5 to 1.0/100,00 per year [74], with higher endemic rates in Southeast Asian countries. NPC arising from the nasopharyngeal epithelium represents at least 70% of tumors of the nasopharynx and, for this reason, will be the focus of the upcoming discussion [74]. Other histologies, including nasopharyngeal lymphoma, constitute a minority of nasopharyngeal malignancies and will therefore not be emphasized in this section. The World Health Organization classifies Assessment of Head and Neck Cancer squamous cell carcinoma of the nasopharynx based on histopathologic features into keratinizing squamous cell carcinoma, nonkeratinizing squamous cell carcinoma, which is further subdivided into differentiated and undifferentiated type, and basaloid squamous cell carcinoma. Alcohol and smoking are associated with NPC, with the strongest link to keratinizing squamous cell carcinoma, which carries the worst prognosis [75]. Almost all nonkeratinizing squamous cell carcinoma and basaloid squamous cell carcinomas are associated with EBV infection with a slightly weaker association of EBV to keratinizing squamous cell carcinoma [18]. The undifferentiated subtype is most common in endemic areas, representing as many as 93% of all cases [75].