Green tea consumption and gastric cancer in Japanese: a pooled analysis of six cohort studies.
BACKGROUND
Previous experimental studies have suggested many possible anti-cancer mechanisms for green tea, but epidemiological evidence for the effect of green tea consumption on gastric cancer risk is conflicting.


OBJECTIVE
To examine the association between green tea consumption and gastric cancer.


METHODS
We analysed original data from six cohort studies that measured green tea consumption using validated questionnaires at baseline. Hazard ratios (HRs) in the individual studies were calculated, with adjustment for a common set of variables, and combined using a random-effects model.


RESULTS
During 2 285 968 person-years of follow-up for a total of 219 080 subjects, 3577 cases of gastric cancer were identified. Compared with those drinking <1 cup/day, no significant risk reduction for gastric cancer was observed with increased green tea consumption in men, even in stratified analyses by smoking status and subsite. In women, however, a significantly decreased risk was observed for those with consumption of > or =5 cups/day (multivariate-adjusted pooled HR = 0.79, 95% confidence interval (CI) = 0.65 to 0.96). This decrease was also significant for the distal subsite (HR = 0.70, 95% CI = 0.50 to 0.96). In contrast, a lack of association for proximal gastric cancer was consistently seen in both men and women.


CONCLUSIONS
Green tea may decrease the risk of distal gastric cancer in women.
Inoue
M
M
Epidemiology and Prevention Division, Research Center for Cancer Prevention and Screening, National Cancer Center, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045 Japan. mnminoue@ncc.go.jp
Sasazuki
S
S
Wakai
K
K
Suzuki
T
T
Matsuo
K
K
Shimazu
T
T
Tsuji
I
I
Tanaka
K
K
Mizoue
T
T
Nagata
C
C
Tamakoshi
A
A
Sawada
N
N
Tsugane
S
S
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D013274:Stomach Neoplasms / Q000453:epidemiology / Q000517:prevention & control*; D011795:Surveys and Questionnaires; D013662:Tea / Q000737:chemistry
D013662:Tea