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Cancer Causes & Control
Published in: Cancer Causes & Control 10/2015

01-10-2015 | Original paper

The Minnesota Green Tea Trial (MGTT), a randomized controlled trial of the efficacy of green tea extract on biomarkers of breast cancer risk: study rationale, design, methods, and participant characteristics

Authors: Hamed Samavat, Allison M. Dostal, Renwei Wang, Sarah Bedell, Tim H. Emory, Giske Ursin, Carolyn J. Torkelson, Myron D. Gross, Chap T. Le, Mimi C. Yu, Chung S. Yang, Douglas Yee, Anna H. Wu, Jian-Min Yuan, Mindy S. Kurzer

Published in: Cancer Causes & Control | Issue 10/2015

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Abstract

Purpose

The Minnesota Green Tea Trial (MGTT) was a randomized, placebo-controlled, double-blinded trial investigating the effect of daily green tea extract consumption for 12 months on biomarkers of breast cancer risk.

Methods

Participants were healthy postmenopausal women at high risk of breast cancer due to dense breast tissue with differing catechol-O-methyltransferase (COMT) genotypes. The intervention was a green tea catechin extract containing 843.0 ± 44.0 mg/day epigallocatechin gallate or placebo capsules for 1 year. Annual digital screening mammograms were obtained at baseline and month 12, and fasting blood and 24-h urine samples were provided at baseline and at months 6 and 12. Primary endpoints included changes in percent mammographic density, circulating endogenous sex hormones, and insulin-like growth factor axis proteins; secondary endpoints were changes in urinary estrogens and estrogen metabolites and circulating F2-isoprostanes, a biomarker of oxidative stress.

Results

The MGTT screened more than 100,000 mammograms and randomized 1,075 participants based on treatment (green tea extract vs. placebo), stratified by COMT genotype activity (high COMT vs. low/intermediate COMT genotype activity). A total of 937 women successfully completed the study and 138 dropped out (overall dropout rate = 12.8 %).

Conclusions

In this paper we report the rationale, design, recruitment, participant characteristics, and methods for biomarker and statistical analyses.
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Metadata
Title
The Minnesota Green Tea Trial (MGTT), a randomized controlled trial of the efficacy of green tea extract on biomarkers of breast cancer risk: study rationale, design, methods, and participant characteristics
Authors
Hamed Samavat
Allison M. Dostal
Renwei Wang
Sarah Bedell
Tim H. Emory
Giske Ursin
Carolyn J. Torkelson
Myron D. Gross
Chap T. Le
Mimi C. Yu
Chung S. Yang
Douglas Yee
Anna H. Wu
Jian-Min Yuan
Mindy S. Kurzer
Publication date
01-10-2015
Publisher
Springer International Publishing
Published in
Cancer Causes & Control / Issue 10/2015
Print ISSN: 0957-5243
Electronic ISSN: 1573-7225
DOI
https://doi.org/10.1007/s10552-015-0632-2

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