Challenging the effectiveness of green tea in primary and tertiary cancer prevention.
OBJECTIVE
Drinking green tea daily is part of Japanese culture, and various studies have revealed that green tea is a cancer preventive. We here review our progress in cancer prevention with green tea on 12 main topics, from basic to clinical level. TOPICS AND METHODS: Biochemical and biological studies of green tea catechins, a prospective cohort study, preclinical safety trials with tablets of green tea extract, double-blind randomized clinical phase II prevention trial for recurrence of colorectal adenomas, and synergistically enhanced inhibition by the combination of green tea catechins and anticancer drugs. All results were significant, including human studies with informed consent.


RESULTS
Drinking 10 Japanese-size cups of green tea per day delayed the cancer onset of humans 7 years for females. For tertiary cancer prevention, consuming 10 cups of green tea per day fortified by green tea tablets, 50 %, significantly prevented the recurrence of colorectal adenomas. A minimum effective amount of green tea catechins for cancer prevention was found in humans. In addition, the combination of green tea catechins and anticancer drugs engendered a new cancer therapeutic strategy.


CONCLUSIONS
The consumption of 10 Japanese-size cups of green tea per day is a significant factor in primary cancer prevention for the general population, and the preventive effect on recurrence of colorectal adenomas in patients is vital evidence in tertiary cancer prevention.
Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima 770-8514, Japan. uv4h-fjk@asahi-net.or.jp
Hirota
H
Fujiki
Kazue
K
Imai
Kei
K
Nakachi
Masahito
M
Shimizu
Hisataka
H
Moriwaki
Masami
M
Suganuma
D000818:Animals; D016588:Anticarcinogenic Agents / Q000627:therapeutic use*; D002392:Catechin / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008297:Male; D009369:Neoplasms / Q000517:prevention & control*; D008517:Phytotherapy / Q000379:methods / Q000639:trends; D010936:Plant Extracts / Q000627:therapeutic use; D013662:Tea / Q000737:chemistry*
D016588:Anticarcinogenic Agents; D010936:Plant Extracts; D013662:Tea; D002392:Catechin