Green tea extracts for the prevention of metachronous colorectal adenomas: a pilot study.
BACKGROUND
Experimental studies indicate the chemopreventive properties of green tea extract (GTE) on colorectal cancer. Epidemiologically, green tea consumption of > 10 cups daily reduced colorectal cancer risk in Japanese. Because colorectal adenomas are the precursors to most sporadic colorectal cancers, we conducted a randomized trial to determine the preventive effect of GTE supplements on metachronous colorectal adenomas by raising green tea consumption in the target population from an average of 6 cups (1.5 g GTE) daily to > or = 10 cups equivalent (2.5 g GTE) by supplemental GTE tablets.


METHODS
We recruited 136 patients, removed their colorectal adenomas by endoscopic polypectomy, and 1 year later confirmed the clean colon (i.e., no polyp) at the second colonoscopy. The patients were then randomized into two groups while maintaining their lifestyle on green tea drinking: 71 patients supplemented with 1.5 g GTE per day for 12 months and 65 control patients without supplementation. Follow-up colonoscopy was conducted 12 months later in 125 patients (65 in the control group and 60 in the GTE group).


RESULTS
The incidence of metachronous adenomas at the end-point colonoscopy was 31% (20 of 65) in the control group and 15% (9 of 60) in the GTE group (relative risk, 0.49; 95% confidence interval, 0.24-0.99; P < 0.05). The size of relapsed adenomas was also smaller in the GTE group than in the control group (P < 0.001). No serious adverse events occurred in the GTE group.


CONCLUSIONS
GTE is an effective supplement for the chemoprevention of metachronous colorectal adenomas.
Shimizu
Masahito
M
Department of Medicine, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu 501-1194, Japan.
Fukutomi
Yasushi
Y
Ninomiya
Mitsuo
M
Nagura
Kazuo
K
Kato
Tomohiro
T
Araki
Hiroshi
H
Suganuma
Masami
M
Fujiki
Hirota
H
Moriwaki
Hisataka
H
D000236:Adenoma / Q000517:prevention & control*; D000328:Adult; D000368:Aged; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000517:prevention & control*; D005260:Female; D006801:Humans; D015994:Incidence; D007564:Japan; D008297:Male; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000517:prevention & control*; D010865:Pilot Projects; D010936:Plant Extracts; D013662:Tea; D016896:Treatment Outcome
D010936:Plant Extracts; D013662:Tea