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Linzhou City has one of the highest incidences of oesophageal cancer in China, and in the world. A case-control study was here conducted to investigate potential risk factors in this area. Linzhou Cancer Registry was used to identify cases of oesophageal cancer, aged between 30 and 75, diagnosed between January 1998 and April 1999. Three neighbourhood controls were selected for each case, matched according to age, sex and village of residence. A total of 211 cases and 633 controls were interviewed. A strong association was found between socio-economic status and the risk of oesophageal cancer. Increased income, residential space and education were all significantly associated with a decreased risk (OR 0.54, 0.36 and 0.30 respectively). Using a drinking water source other than tap water was significantly associated with an increased risk (OR 5.49). The consumption of beans, vegetables and vinegar all showed a protective effect with odds ratios of 0.37, 0.44 and 0.37 respectively. Preferences for a low salt diet or a high salt diet were both associated with an increased risk. It can be concluded that in Linzhou, oesophageal cancer is a disease related to poverty. Having a drinking water source other than tap water increases the risk of oesophageal cancer. As in other populations, a high consumption of vegetables and beans are associated with a decreased risk and a preference for a high salt diet is associated with an increased risk.

A case-control study was conducted to investigate risk factors for stomach cancer in a rural population in China. Linzhou Cancer Registry was used to identify cases of stomach cancer, aged between 30 and 75 years, diagnosed between January 1998 and April 1999. Three neighbourhood controls were selected for each case, matched according to age, sex and village of residence. A total of 210 cases and 630 controls were interviewed. Conditional logistic regression was used to estimate odds ratios (OR) for factors associated with the risk of cancer. Among characteristics of the residential environment, significantly increased risk was found for: frequent irritation on eyes or throat by soot (OR 5.54, 95% CI 1.42-21.65, p for trend <0.01). This effect was particularly strong in women (OR 19.5, 95% CI 1.28-297.09, p for trend =0.01). Dietary factors that were significantly associated with an increased risk were food grains other than rice, wheat and maize (OR 2.93, 95% 1.16-7.38), pickled or salted vegetables (OR 3.99, 95% CI 1.63-9.75) and preference for a high salt diet (OR 2.58, 95% CI 1.56-4.26). The consumption of vegetables showed a protective effect with an odds ratio of 0.27 (95% CI 0.11-0.61). It follows that a developing economy and improvement in living standards, with associated increased intake of fruit and vegetables and reduced consumption of salt, can contribute to a reduction in the incidence of stomach cancer in the Linzhou population.