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Cancer Causes Control. 2015 Oct;26(10):1405-19. doi: 10.1007/s10552-015-0632-2. Epub 2015 Jul 24.

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.

Author information

1
Department of Food Science and Nutrition, University of Minnesota, St Paul, MN, USA.
2
Division of Cancer Control and Population Sciences, University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA.
3
Department of Radiology, Center for Magnetic Resonance Research, University of Minnesota Medical School, Minneapolis, MN, USA.
4
Cancer Registry of Norway, Oslo, Norway.
5
Department of Nutrition, University of Oslo, Oslo, Norway.
6
Department of Preventive Medicine, University of Southern California Keck School of Medicine, Los Angeles, CA, USA.
7
Department of Family Medicine and Community Health, University of Minnesota Medical School, Minneapolis, MN, USA.
8
Department of Laboratory Medicine and Pathology, University of Minnesota Medical School, Minneapolis, MN, USA.
9
Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, MN, USA.
10
Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA.
11
Department of Chemical Biology, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, NJ, USA.
12
Department of Medicine, University of Minnesota, Minneapolis, MN, USA.
13
Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA.
14
Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA.
15
Department of Food Science and Nutrition, University of Minnesota, St Paul, MN, USA. mkurzer@umn.edu.

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.

KEYWORDS:

Breast cancer; Green tea; Mammographic density; Postmenopausal women; Sex hormones

PMID:
26206423
PMCID:
PMC4567901
DOI:
10.1007/s10552-015-0632-2
[Indexed for MEDLINE]
Free PMC Article

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