Experimental studies have shown the chemopreventive properties of green tea extract (GTE) on colorectal cancer. And colorectal adenomas are precursors to colorectal cancers. The aim of this study is to determine the preventive effect of GTE supplements on metachronous colorectal adenomas by giving GTE tablets of which are equivalent of 9 cup-of-green tea per day (0.9 g/day GTE, 0.6 g/day Epigallocatechin gallate (EGCG).

The subjects who had undergone complete removal of colorectal adenomas by endoscopic polypectomy have been enrolled since June 2010. They were then randomized into two groups as follows: supplementation group (0.9 g GTE per day for 12 months) or control group without GTE supplementation. Follow-up colonoscopy was conducted in 12 months. A structured 72-h recall at baseline and the 1-year follow-up was used to assess dietary factors, and to evaluate rectal mucosal proliferation index (RMPI) using known proliferation markers (Ki-67/PCNA), at least 2 random biopsies of rectal mucosa were taken. A sample size of 176 patients (88 per each group) was calculated to give the study 80% power to detect a difference, assuming a two-sided significance test at the 0.05 level.

Inclusion Criteria:

- subjects who present one or more adenomatous polyps on colonoscopy.

Exclusion Criteria:

• subjects who denied to participate in this study
• subjects who present inflammatory bowel diseases such as ulcerative colitis or crohn's disease
• subjects who received partial or total colectomy due to colon cancer or other colonic diseases.
• subjects who are pregnant
• subjects who are on aspirin or NSAIDS for any reasons
• subjects who have received a transplant of any major organ or who are on immunosuppressants for any reason
• subjects who are unable to perform a bowel prep or who present poor bowel prep for colonoscopy