Consumption of salted fish and other risk factors for nasopharyngeal carcinoma (NPC) in Tianjin, a low-risk region for NPC in the People's Republic of China

The dietary habits, occupational exposures, use of tobacco and alcohol, and medical history were compared among 100 patients with histologically confirmed nasopharyngeal carcinoma (NPC) in Tianjin City, People's Republic of China, and 300 neighborhood controls who were individually matched to the patients with regard to age (within 5 yr), sex, and race (Han). Exposure to salted fish was significantly associated with an increased risk of NPC. Four characteristics of exposure to salted fish independently contributed to the increased risk: (a) earlier age at first exposure, (b) increasing duration of consumption, (c) increasing frequency of consumption, and (d) cooking the fish by steaming it rather than frying, grilling, or boiling it. In addition, significant associations were observed for consumption in childhood of salted shrimp paste (increased risk) and carrots (reduced risk), and the three dietary effects (i.e., those from consumption of salted fish, salted shrimp paste, and carrots) were independent of each other. None of the non-dietary factors studied were significantly associated with NPC risk.