| Gastric cancer is one kind of the most common malignant cancers in the world. In China, the mortality of gastric cancer is about 25.16/100000 per year, which is the highest among malignant cancers. Despite a decreasing trend observed in parts of western countries, the mortality of gastric cancer is estimated to be increasing in many cities of our country, especially in eastern coastlands including Zhoushan Islands, the fourth archipelago and also the largest fishing ground in China. According to data from the surveillance of malignant cancers, the age-standardized annual mortality of gastric cancer is about 36.71 /100000, which is highly over the national level.The occurrence of the gastric cancer is ascribed to multiple risk factors, genes and stages. Environmental factors, especially diet factors, are the major causes of gastric cancer. While gastric cancer has an obvious incline of familial aggregations, the incidence rate in the family clan is 2 to 3 higher than that of public population, which shows that heredity is also an important factor in contrast to environmental factors.To investigate risk factors for this common cancer in the coastal areas, we conducted a population-based case-control study in Zhoushan Islands.MATERIAL AND METHODSThe data-collection period for the study spanned through the whole year of 2001 and comprised three major islands of Zhoushan, Zhejiang Province. The study population included 138 newly diagnosed patients with gastric cancer between December 1, 2000 and November 30, 2001 and 140 controls as a representative sample of residents in the same area, which frequency-matched to the expected distributions of cases by gender, age (10-year groups) and resident islands. All of the controls had no neoplasm and serious gastrointestinal-tract diseases.A constructed questionnaire elicited information on demographic and socio-economic conditions, diet, history of selected diseases, family history of cancer, occupation and psychological factors. Each subject was interviewed face-to-face by trained interviewers. For each food, amounts consumed were estimated according to models of the more frequently consumed foods for the accuracy of survey.Otherwise, the data on concentration of heavy metals and poisons in diet was from the detection to parts of fishes in the Center for Disease Prevention and Control of Zhoushan, which could not be acquired from the Chinese Food Composition Tables directly.The data were processed with software of Matlab6.0, SPSS 10.0 and SAS6.12 in personal computer after verified. The statistical methods included chi-square test; nonparametric Median/Wilcoxon test because of biased distributions of the data, which couldn't be transformed into normal with logarithmic transformations etc; unconditional logistic regression models and Falconer method for the estimation of heritability.RESULTS1. Socio-economic conditions and gastric cancerThe incidence rate of gastric cancer was lower among persons who had higher average per capita income 20 years ago, which showed a median protective effect (OR=0.51, 95%CI.- 0.32-0.82).2. Life style and gastric cancerDrinking river water frequently was the risk factor of gastric cancer (OR=3.33, 95%CI: 1.39-8.01), and a significant time-effect response was found. As to the relationship between alcohol drinking and gastric cancer, the result showed that only yellow-wine drinking was significantly associated with GC (OR=1.81, 95%CI: 1.21-2.71), and the risk also elevated with increasing consumption of this kind of wine. Drinking tea had a protective effect to GC (OR=0.51, 95%CI: 0.29-0.91), which was almost the most consistent finding. But not all kinds of tea had the function, only green tea showed this protective effect in our research.3. Diet and gastric cancerGastric cancer was more related to such dietary habits as hot diet, roasting and regular dietary time. Among them, hot diet was showed as a risk factor while the other two habits as protective factors (the OR values were 1.48 -, 0...
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