Walsh & Hoyt: Nasopharyngeal Carcinomas

Malignant carcinomas originating within the nasopharynx are rare. In North America, they constitute only about 0.25% of all cancers, and their incidence is about 5 per 1,000,000. They are far more common among the Chinese, who account for about 18% of all malignant neoplasms. The incidence of nasopharyngeal carcinoma is even higher among southern Chinese and among the Chinese of Taiwan. Hsu et al. estimated that nasopharyngeal carcinoma is the most common cancer in men and the third most common cancer in women in Taiwan. Interestingly, the incidence of nasopharyngeal carcinoma among Chinese born in the United States is consistently lower than that among native-born Chinese. This finding suggests that environmental factors contribute to the cause of the disease. Also implicated as causes of nasopharyngeal carcinoma are infection with Epstein-Barr (EB) virus, heavy cigarette smoking, exposure to polycyclic hydrocarbons, intake of nitrosamines from dry salted fish, chronic nasal and sinus infections, and poor hygiene. Nasopharyngeal carcinomas most often become symptomatic between ages 4060 with bimodal peaks in the second and sixth decades, but they may occur in childhood. Men are affected twice as often as women.