Preserved foods in relation to risk of nasopharyngeal carcinoma in Shanghai, China

A population-based case-control study was conducted in Shanghai, China, to investigate the association between dietary factors and risk of nasopharyng eal carcinoma (NPC). The study included 935 NPC patients aged 15 to 74 year s and 1,032 community controls. Exposures to salted fish and other protein- containing preserved food were associated with increased risk of NPC. Indiv iduals who ate salted fish at least once a week had an 80% increase in risk of NPC relative to those who ate salted fish less than once a month (p = 0 .07). Compared with those in the lowest quartile of protein-containing pres erved foods, subjects in the highest quartile of intake experienced a stati stically significant 78% increase in risk of NPC [odds ratio (OR) = 1.78, 9 5% confidence interval (CI) = 1.37-2.31], with a dose-dependent relationshi p (p for linear trend < 0.001). A similar association between intake of pre served vegetables and NPC risk was observed (OR = 1.39, p for linear trend = 0.003). In contrast, high intake of oranges/tangerines was associated wit h a statistically significant reduction in risk of NPC (OR = 0.55, p for li near trend < 0.001). When we examined the joint effect of preserved food an d oranges/tangerines on risk of NPC, subjects in the highest tertile of pre served food and the lowest tertile of orange/tangerine intake had a 3-fold increase in risk (95% CI 2.08-4.91) compared with those in the lowest terti le of preserved food and the highest tertile of orange/tangerine intake. (C ) 2000 Wiley-Liss, Inc.