On the epidemiology of nasopharyngeal carcinoma

Publisher Website
Google Scholar
Abstract
The incidence of nasopharyngeal carcinoma is high in Chinese in South East China and in those living in a traditional Chinese manner in the countries of South East Asia. The related Mongoloid peoples of Japan and Korea have a low incidence, as do the Caucasians of Europe, America and India. In Chinese born abroad and living in a “Western”‐type environment in Australia, Hawaii and California the incidence falls significantly. This suggests that the high incidence in the Chinese relates to a genetically determined racial or “line” predisposition combined with environmental factors or to environmental factors alone. In Kenya, ethnic origin does not relate to incidence which depends on environmental factors only. The possible significance of genetic factors cannot be assessed until adequate information on the genetic profiles of racial groups with high and low incidences is available.Different environmental factors may be of importance. Biologic agents such as fungi or viruses may be of importance in some areas, in others a physical or chemical agent may be of significance, or the cancer may arise following exposure to a combination of factors. In some areas inhalation of polynuclear hydrocarbons may be of importance, in others the ingestion of nitrosamine‐like compounds, and these external agents may only be effective if combined with a viral infection, possibly the Epstein‐Barr virus or with a particular nutritional or hormonal status.The local tissue sensitivity is the factor which determines the response to any particular external agent. Examination of the external environment is, perhaps, of less importance than that of the milieu intérieur, as it is now recognized that the stability of the respiratory epithelium is affected by hormonal and nutritional factors. Universally the incidence in men is higher than in women, and this may relate to their different internal environments.