A randomized controlled trial of green tea extract supplementation and mammographic density in postmenopausal women at increased risk of breast cancer

Hamed Samavat, Giske Ursin, Tim H. Emory, Eunjung Lee, Renwei Wang, Carolyn J. Torkelson, Allison M. Dostal, Karen Swenson, Chap T. Le, Chung S. Yang, Mimi C. Yu, Douglas Yee, Anna H. Wu, Jian Min Yuan, Mindy S. Kurzer

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

Epidemiologic and animal studies suggest a protective role of green tea against breast cancer. However, the underlying mechanism is not understood. We conducted a randomized, double-blinded, placebo-controlled phase II clinical trial to investigate whether supplementation with green tea extract (GTE) modifies mammographic density (MD), as a potential mechanism, involving 1,075 healthy postmenopausal women. Women assigned to the treatment arm consumed daily 4 decaffeinated GTE capsules containing 1,315 mg total catechins, including 843 mg epigallocatechin-3-gallate (EGCG) for 12 months. A computer-assisted method (Madena) was used to assess MD in digital mammograms at baseline and month 12 time points in 932 completers (462 in GTE and 470 in placebo). GTE supplementation for 12 months did not significantly change percent MD (PMD) or absolute MD in all women. In younger women (50–55 years), GTE supplementation significantly reduced PMD by 4.40% as compared with the placebo with a 1.02% PMD increase from pre- to postintervention (P ¼ 0.05), but had no effect in older women (Pinteraction ¼ 0.07). GTE supplementation did not induce MD change in other subgroups of women stratified by catechol-O-methyltransferase genotype or level of body mass index. In conclusion, 1-year supplementation with a high dose of EGCG did not have a significant effect on MD measures in all women, but reduced PMD in younger women, an age-dependent effect similar to those of tamoxifen. Further investigation of the potential chemopreventive effect of green tea intake on breast cancer risk in younger women is warranted.

Original languageEnglish (US)
Pages (from-to)710-718
Number of pages9
JournalCancer Prevention Research
Volume10
Issue number12
DOIs
StatePublished - Dec 1 2017

Bibliographical note

Funding Information:
We sincerely thank the Minnesota Green Tea Trial (MGTT) participants for taking part in this research. We also acknowledge all staff at the University of Minnesota (J. Mobeck-Wilson, W.E. Smith, M. Wachter, S. Bedell, S. Kjellberg Muehlhausen, A. Brehm, K. Ringsak, L. Carpenter, A. Schumacher, K. Mischke, study radiologists Drs. J. Kuehn-Hajder and M. Mckeon, and study pharmacist Dr. D. Luke), graduate students contributing to the MGTT (A. Perry and A.R. Newman), and staff at the Oncology Research Department of the Park Nicollet Institute (A. Egan and J. Nissen) for their assistance with participant recruitment, mammogram screening, conducting clinic visits and laboratory measurements, data entry, and all other administrative tasks. We also thank our Data and Safety Monitoring Board members (P. Brown, chair; S. Groshen; and C. Norton) for monitoring the trial's integrity, progress, and safety. This work was supported by grants from NIH/NCI (R01 CA127236, T32CA186873, and T32CA132670), Department of Defense/U.S. Army Medical Research and Materiel Command (W81XWH-11-1-0013), the University of Minnesota Graduate School, Doctoral Dissertation Fellowship, the Minnesota Agricultural Experiment Station (project #MIN-18-103); and the National Center for Advancing Translational Sciences of the National Institutes of Health (UL1TR000114). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

Funding Information:
This work was supported by grants from NIH/NCI (R01 CA127236, T32CA186873, and T32CA132670), Department of Defense/U.S. Army Medical Research and Materiel Command (W81XWH-11-1-0013), the University of Minnesota Graduate School, Doctoral Dissertation Fellowship, the Minnesota Agricultural Experiment Station (project #MIN-18-103); and the National Center for Advancing Translational Sciences of the National Institutes of Health (UL1TR000114).

Publisher Copyright:
©2017 AACR.

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