INFLUENCE OF DRINKING GREEN TEA ON BREAST-CANCER MALIGNANCY AMONG JAPANESE PATIENTS

Inhibitory effects of green tea on carcinogenesis have been investigat ed in numerous laboratory studies using (-)-epigallocatechin gallate ( EGCG) or crude green tea extract, and there is also some epidemiologic evidence, Further, EGCG has been reported to inhibit the growth of ca ncer cells, lung metastasis in an animal model, and urokinase activity . In this study, we first examined the association between consumption of green tea prior to clinical cancer onset and various clinical para meters assessed al surgery among 472 patients with stage I, II, and II I breast cancer. We found that increased consumption of green tea was closely associated with decreased numbers of axillary lymph node metas tases among premenopausal patients with stage I and II breast cancer a nd with increased expression of progesterone receptor (PgR) and estrog en receptor (ER) among postmenopausal ones, Since these are potential prognostic factors, we then investigated the prognosis of breast cance r with special reference to consumption of green tea, in a follow-up s tudy of these patients, We found that increased consumption of green t ea was correlated with decreased recurrence of stage I and II breast c ancer (P<0.05 for crude disease-free survival); the recurrence rate wa s 16.7 or 24.3% among those consuming greater than or equal to 5 cups or less than or equal to 4 cups per day, respectively, in a seven-gear follow-up of stage I and IL breast cancer, and the relative risk of r ecurrence was 0.564 (95% confidence interval, 0.350-0.911) after adjus tment for other lifestyle factors, However, net improvement in prognos is was observed in stage III breast canter, Our results indicate that increased consumption of green tea prior to clinical cancer onset is s ignificantly associated with improved prognosis of stage I and II brea st cancer, and this association may be related to a modifying effect o f green tea on the clinical characteristics of the cancer.