Nasopharyngeal carcinoma: epidemiology and dietary factors.

Nasopharyngeal carcinoma (NPC) is a disease with a remarkable racial and geographical distribution. It is very rare (incidence of less than 1 per 100,000 person-years) in most parts of the world, and in only a handful of populations does this low-risk profile deviate; these groups include people in southern China, Eskimos and other natives of the Arctic region, natives of south-east Asia, and the mainly Arab populations of North Africa and Kuwait. Convincing evidence implicates dietary factors as the primary cause of NPC among Chinese. A series of case-control studies conducted in various Chinese populations with distinct risks of NPC, ranging from the very high-risk Cantonese populations to the relatively low-risk northern Chinese, have suggested that ingestion of salted fish and other kinds of preserved foods constitutes the most important cause of NPC among these people. Preliminary data on Malays in south-east Asia, Eskimos in Alaska and Arabs of North Africa also suggests that ingestion of preserved foods by these population groups may be responsible for their raised incidence of NPC.