Additional symptoms of NPC include facial pain or numbness, blurred or double vision, trouble opening the mouth, or recurring ear infections. If the ear infection does not present with an upper respiratory tract infection, then an examination should be done on the nasopharynx. This is due to the fact that, in adults, ear infections are less common than in children. Signs and symptoms related to the primary tumor include trismus, pain, otitis media, nasal regurgitation due to paresis (loss of or impaired movement) of the soft palate, hearing loss and cranial nerve palsy (paralysis). Larger growths may produce nasal obstruction or bleeding and a "nasal twang". Metastatic spread may result in bone pain or organ dysfunction. Rarely, a paraneoplastic syndrome of osteoarthropathy (diseases of joints and bones) may occur with widespread disease. Causes
NPC is caused by a combination of factors: viral, environmental influences, and heredity. The viral influence is associated with infection with Epstein–Barr virus (EBV). The Epstein-Barr virus is one of the most common viruses. 95% of all people in the U.S. are exposed to this virus by the time they are 30–40 years old. The World Health Organization does not have set preventative measures for this virus because it is so easily spread and is worldwide. Very rarely does Epstein-Barr virus lead to cancer, which suggests a variety of influencing factors. Other likely causes include genetic susceptibility, consumption of food (in particular salted fish) containing carcinogenic volatile nitrosamines.
It is sometimes referred to as Cantonese cancer (廣東癌) because it occurs in about 25 cases per 100,000 people in this region, 25 times higher than the rest of the world. It is also quite common in Taiwan. This could be due to the Southeast Asian diet or that Southern Chinese people such as the Cantonese and Taiwanese have Southeast Asian ancestry (such as the proto-Kra-Dai speaking peoples and proto-Austronesian peoples) via ancient intermarriages with Han Chinese from Northeast Asia which led to the transmission of a genetic risk for nasopharynx cancer. While NPC is seen primarily in middle-aged persons in Asia, a high proportion of African cases appear in children. The cause of increased risk for NPC in these endemic regions is not clear. In low-risk populations, such as in the United States, a bimodal peak is observed. The first peak occurs in late adolescence/early adulthood (ages 15–24 years), followed by a second peak later in life (ages 65–79 years). See also
Endoscopic nasopharyngectomy
Lymphoepithelioma-like carcinoma

References
External links

Cancer Management Handbook: Head and Neck Tumors
Clinically reviewed nasopharyngeal cancer information for patients from Cancer Research UK