Walter Oliver

A case‐control study of gastric cancer in Venezuela

A case‐control study to evaluate risk factors for gastric cancer was carried out among 292 cases of gastric cancer and 485 controls in a high‐risk area of Venezuela. Subjects were interviewed using a structured questionnaire, which elicited information on residential history, socio‐economic status, family history of gastric diseases, smoking, drinking and dietary habits. Habitual diet was estimated from a meal‐structured food frequency questionnaire on 75 food items. There was a strong inverse association with social class, as measured by education and by indicators of poverty. The results of the dietary analysis suggest that a diet high in starch and low in meat, fish and fresh vegetables increases risk of gastric cancer. A protective effect was observed for frequent consumption of allium vegetables. Inverse associations were found with height, which may reflect nutritional status in childhood, and with refrigerator use in the first two decades of life. Alcohol and tobacco consumption was investigated among males only, since the prevalence of alcohol and tobacco use was very low in females. Alcohol drinkers were at higher risk than non‐drinkers and there was a small excess risk for current smokers compared with never smokers. There was some evidence of familial aggregation of gastric cancer. These findings will have important implications in planning preventive strategies for gastric cancer in Venezuela.

Determinants of plasma anti-oxidant vitamin levels in a population at high risk for stomach cancer.

Our objective was to identify the determinants of plasma levels of anti‐oxidant vitamins which have been linked with decreased risk of cancer and other chronic diseases. Correlation analyses were performed between baseline plasma levels of ascorbic acid, α‐ and β‐carotenes, cryptoxanthin, lycopene and α‐ and γ‐tocopherols and baseline information on dietary and other demographic and life‐style factors among 1,364 subjects 35–69 years of age, who are participants in a chemoprevention trial on pre‐cancerous lesions of the stomach in Venezuela. Males had lower levels of ascorbic acid, α‐ and β‐carotene and cryptoxanthin and higher levels of α‐tocopherol than females. This finding was confirmed in non‐smokers and non‐drinkers. In females, but not in males, age was positively associated with levels of ascorbic acid, cryptoxanthin, α‐ and β‐carotene and γ‐tocopherol. Male tobacco users had lower plasma levels of ascorbic acid, α‐ and β‐carotene and cryptoxanthin than non‐users, and regular alcohol drinkers had a decreased plasma levels of β‐carotene compared with non‐drinkers. Female tobacco users had lower levels of ascorbic acid and cryptoxanthin than non‐users, and regular alcohol drinkers had lower levels of ascorbic acid and lycopene than non‐drinkers. Frequencies of consumption of fresh fruits, fruit juice, raw vegetables and plantains showed weak positive associations with plasma levels of several vitamins studied in both sexes. Sex, age in females, tobacco and alcohol use and dietary consumption affected plasma anti‐oxidant vitamin levels in this population significantly. These factors may influence the effect of anti‐oxidant treatment in intervention trials.