Epidemiological research in stomach cancer: progress over the last ten years

Abstract

In this paper the progress of epidemiological research in stomach cancer during 1980-1990 is reviewed in respect to regional variation, etiology, and formation of carcinogens. The evaluation of 4 cohort and 16 case-control studies revealed a consistently inverse relationship of stomach cancer risk with raw vegetables, fruit, and wholemeal bread consumption and with vitamin C and carotene intake. Milk, cooked vegetables and vitamins A and E were not consistently found to be related to stomach cancer risk. Positive associations of increasing consumption with stomach cancer risk were occasionally found for processed or particularly prepared meat and fish, and for nitrite. Dietary nitrate intake did not appear to be related to stomach cancer risk in these studies. This latter observation is also supported by metabolic studies in high- and low-risk areas for stomach cancer. Consistently among studies, increased risk for stomach cancer was also found for later availability of refrigeration facilities in the household, non-centralized water supply (especially well water), and high salt intake. Prospective studies agreed in an increased risk for stomach cancer for cigarette smoking, but not for alcohol drinking, whereas case-control studies showed divergent results on these factors. Recent metabolic studies in high- and low-risk areas for stomach cancer or in groups with precursor lesions, with the N-nitrosoproline test as a marker for endogenous nitrosation, revealed inconsistent results. Higher nitrite concentration and increased pH in stomach juice were found to be associated with precursor conditions for stomach cancer. It is still not clear whether intake of preformed carcinogens or endogenous formation in the stomach with or without the inclusion of nitrite is the most important source of tumor-initiating or -promoting substances. Preservation or preparation of meat and fish may play an important role in this process, and vitamin C may be an inhibiting substance.

Severe atrophic gastritis with Helicobacter pylori infection and gastric cancer

“…However, it seems that H. pylori infection alone is neither necessary nor sufficient for the development of gastric cancer. Dietary factors, such as excessive salt intake and diets low in fresh fruits and vegetables; smoking; and genetic factors may still play important roles in gastric cancer carcinogenesis [30,[43][44][45][46][47]. The role of H. pylori infection in the complex multifactorical carcinogenesis of gastric cancer needs to be explored further in the light of the multistep theory of gastric carcinogenesis.…”

Declining incidence is greater for esophageal than gastric cancer in Shanghai, People's Republic of China

“…With the increasing availability of fresh vegetables, meat and fish in Shanghai (Lu & Xiu, 1987), consumption of preserved, particularly salted and moldy foods, has declined over the past several decades. These foods have been linked to an increased risk of both esophageal (Ziegler et al, 1981;Cheng et al, 1992;Wang et al, 1992) and gastric (You et al, 1988;Buiatti et al, 1989;Boeing, 1991;Boeing et al, 1991;Ji et al, 1992) cancers in previous studies, so that lower consumption may contribute to the declining rates of these cancers, particularly cancer of the esophagus, since these foods appear to be more closely related to esophageal cancer risk Cheng et al, 1992). Refrigeration, shown to be associated with reduced risk of gastric cancer among other populations (Coggon et al, 1989), probably has not yet played a major role in Shanghai as widespread availability is only a recent phenomenon.…”

“…The persistence of factors that have been associated with stomach cancer risk, such as starchy foods or carbohydrates, the major energy sources in the Chinese diet (Graham et al, 1990;Kneller et al, 1992), irregular eating habits (Boeing et al, 1991), high salt intake (Boeing, 1991), and Helicopbacter pylori infection (Nomura et al, 1991) China (Li et al, 1989). Increased exposure to these two agents in Shanghai are not yet reflected in the trends.…”

A nested case–control study of stomach cancer in relation to green tea consumption in Japan

“…The relative risk (RR) and its 95% confidence interval (CI) were calculated based on the regression coefficient and its standard error (Cox, 1972), for an indicator term corresponding to the level of an independent variable. For multivariate analysis, several factors were listed as potential confounders according to epidemiological studies (Boeing, 1991;Hoshiyama and Sasaba, 1992;World Cancer Research Fund, 1997;Hoshiyama et al, 2002;Yatsuya et al, 2002). Trends of association were assessed by the regression model assigning scores (0 -4) to the levels of the independent variables.…”