Sinicrope 2017.

Study characteristics
Methods	RCT, parallel, double‐blind in USA
Participants	39 (male/female: 14/25) participants: participants with prior advanced adenoma (N = 37), or colon cancer (N = 2) Inclusion criteria: at least 5 rectal ACF at baseline. 19 (male/female: 6/13) participants in the treatment group and 20 (male/female: 8/12) in the control group
Interventions	Group A: GTE (Polyphenon E, 2 capsules of 200 mg twice/d = 800 mg) containing 400 mg of EGCG Group B: placebo Duration: 6 months
Outcomes	Change in rectal ACF Safety data
Green tea in exposure categories	N/A
Notes	ClinicalTrial.gov identifier: NCT01606124
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Described as randomised in the abstract and in ClinicalTrials.gov
Allocation concealment (selection bias)	Unclear risk	No information about concealment process
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Probably done as it is described as double‐blind and placebo capsules were implemented
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Probably done as it is described as double‐blind and placebo capsules were implemented, but no explicit statement
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	All results reported for all included participants
Selective reporting (reporting bias)	Low risk	Results for the trial reported on (ClinicalTrials.gov identifier (NCT number): NCT01606124)
Other bias	Low risk	No withdrawals reported