TEA AND COFFEE CONSUMPTION AND THE RISK OF DIGESTIVE-TRACT CANCERS - DATA FROM A COMPARATIVE CASE-REFERENT STUDY IN JAPAN

Objectives: The purpose of this study was to examine the hypothesis th at tea and coffee consumption have a protective effect against develop ment of digestive tract cancers. Methods: A comparative case-referent study was conducted using Hospital-based Epidemiologic Research Progra m at Aichi Cancer Center (HERPACC) data from 1990 to 1995 in Nagoya, J apan. This study comprised 1,706 histologically diagnosed cases of dig estive tract cancers (185 esophagus, 893 stomach, 362 colon, 266 rectu m) and a total of 21,128 non-cancer outpatients aged 40 years and over . Logistic regression was used to analyze the data, adjusting for gend er; age; year and season at hospital-visit; habitual smoking and alcoh ol drinking; regular physical exercise; fruit, rice, and beef intake; and beverage intake. Results: The odds ratio (OR) of stomach cancer de creased to 0.69 (95 percent confidence interval [CI] = 0.48-1.00) with high intake of green tea (seven cups or more per day). A decreased ri sk was also observed for rectal cancer with three cups or more daily i ntake of coffee (OR = 0.46, CI = 0.26-0.81). Conclusions: The results suggest the potential for protective effect against site-specific dige stive tract cancer by consumption of green tea and coffee, although mo st associations are limited only to the upper category of intake and h ave no clear explanation for site-specificity.