Citations: 1-3
<1>
Authors
Otsuka T. Ogo T. Eto T. Asano Y. Suganuma M. Niho Y.
Institution
First Department of Internal Medicine, Faculty of Medicine, Kyushu
University, Fukuoka, Japan.
Title
Growth inhibition of leukemic cells by (-)-epigallocatechin gallate, the main
constituent of green tea.
Source
Life Sciences. 63(16):1397-403, 1998.
Abstract
In this report, we presented the results that EGCG, the main constituent of
the polyphenols present in Japanese green
tea inhibited growth of leukemic cell lines of both human
and mice. The proliferation of human leukemic cell lines and mouse NFS60 cell
line was inhibited by EGCG. Sensitivity of each line to EGCG was different,
and more than 50% of DNA synthesis was reduced in all the cell lines in the
presence of 50 microM EGCG. On the other hand, normal hematopoietic
progenitor cells retained their natural function of supplying mature cells of
various lineages in the presence of less than 10 microM EGCG in vitro. Even
in the presence of 100 microM EGCG, half the colonies containing all the
lineages of cells were developed. All the dead cells of each line showed
characteristics of apoptosis, which might be due to inhibition by EGCG of
growth factors' signaling. Besides anticarcinogenic activity, EGCG is
expected to have a new function for leukemia therapy without side effects.
<2>
Authors
Nakachi K. Suemasu K. Suga K. Takeo T. Imai K. Higashi Y.
Institution
Department of Epidemiology, Saitama Cancer Center Research Institute.
Title
Influence of drinking green tea on breast
cancer malignancy among Japanese patients.
Source
Japanese Journal of Cancer Research. 89(3):254-61, 1998 Mar.
Abstract
Inhibitory effects of green tea on
carcinogenesis have been investigated 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 cancer 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
parameters assessed at surgery among 472 patients with stage I, II, and III
breast cancer. We found that increased consumption of green
tea was closely associated with decreased numbers of
axillary lymph node metastases among premenopausal patients with stage I and
II breast cancer and with increased expression of progesterone receptor (PgR)
and estrogen receptor (ER) among postmenopausal ones. Since these are
potential prognostic factors, we then investigated the prognosis of breast
cancer with special reference to consumption of green
tea, in a follow-up study of these patients. We found that
increased consumption of green tea was
correlated with decreased recurrence of stage I and II breast cancer (P <
0.05 for crude disease-free survival); the recurrence rate was 16.7 or 24.3%
among those consuming > or = 5 cups or < or = 4 cups per day, respectively,
in a seven-year follow-up of stage I and II breast cancer, and the relative
risk of recurrence was 0.564 (95% confidence interval, 0.350-0.911) after
adjustment for other lifestyle factors. However, no improvement in prognosis
was observed in stage III breast cancer. Our results indicate that increased
consumption of green tea prior to clinical
cancer onset is significantly associated with improved prognosis of stage I
and II breast cancer, and this association may be related to a modifying
effect of green tea on the clinical
characteristics of the cancer.
<3>
Authors
Imai K. Suga K. Nakachi K.
Institution
Department of Epidemiology, Saitama Cancer Center Research Institute, Japan.
Title
Cancer-preventive effects of drinking green
tea among a Japanese population.
Source
Preventive Medicine. 26(6):769-75, 1997 Nov-Dec.
Abstract
BACKGROUND: Laboratory studies have revealed the cancer preventive effects of
green tea, so the association between
green tea consumption and cancer was
examined in a human population. METHODS: The association between
green tea consumption and cancer incidence
was studied in our prospective cohort study of a Japanese population. We
surveyed 8,552 individuals over 40 years of age living in a town in Saitama
prefecture on their living habits, including daily consumption of
green tea. During the 9 years of follow-up
study (71,248.5 person-years), we identified a total of 384 cases of cancer
in all sites. RESULTS: We found a negative association between
green tea consumption and cancer incidence,
especially among females drinking more than 10 cups a day. The slowdown in
increase of cancer incidence with age observed among females who consumed
more than 10 cups a day is consistent with the finding that increased
consumption of green tea is associated with
later onset of cancer. Age-standardized average annual incidence rate was
significantly lower among females who consumed large amounts of
green tea. Relative risk (RR) of cancer
incidence was also lower among both females (RR = 0.57, 95% CI = 0.33-0.98)
and males (RR = 0.68, 95% CI = 0.39-1.21) in groups with the highest
consumption, although the preventive effects did not achieve statistical
significance among males, even when stratified by smoking and adjusted for
alcohol and dietary variables. CONCLUSION: Our epidemiological study showed
that green tea has a potentially preventive
effect against cancer among humans.