Safety Issues of Soy Phytoestrogens in Breast Cancer Patients
Authors: Mário de Lemos, Cheri L. Van Patten, Karen A. Gelmon, Ivo A. Olivotto
Journal: Journal of Clinical Oncology (2002)

Article Tools SPECIAL DEPARTMENTS Article Tools OPTIONS & TOOLS Export Citation Track Citation Add To Favorites Rights & Permissions COMPANION ARTICLES No companion articles ARTICLE CITATION DOI: 10.1200/JCO.2002.20.13.3040 Journal of Clinical Oncology - published online before print September 21, 2016 PMID: 12089239 Safety Issues of Soy Phytoestrogens in Breast Cancer Patients Mário de LemosxMário de LemosSearch for articles by this author Cheri L. Van PattenxCheri L. Van PattenSearch for articles by this author , Karen A. GelmonxKaren A. GelmonSearch for articles by this author , Ivo A. OlivottoxIvo A. OlivottoSearch for articles by this author Show More Vancouver, British Columbia, CanadaBritish Columbia Cancer Agency, Vancouver, British Columbia, CanadaBritish Columbia Cancer Agency, Victoria, British Columbia, Canada https://doi.org/10.1200/JCO.2002.20.13.3040 First Page Full Text PDF Figures and Tables © 2002 by American Society of Clinical OncologyjcoJ Clin OncolJournal of Clinical OncologyJCO0732-183X1527-7755American Society of Clinical OncologyResponse01072002In Reply:The safety of phytoestrogens in women with breast cancer is controversial, and this issue was specifically addressed in the consent form for our study.1 The potential risk was discussed with women. Thirteen eligible women declined randomization as indicated in our article in Figure 1. At least some of these women who declined did so because of their concerns about phytoestrogen risks.At the time the study was designed in 1997, there were limited data on the risk of phytoestrogens, and even today, most studies have been based on the effects of genistein alone rather than soy foods. Additionally, soy foods contain a number of nonhormonal compounds with potential anticancer activity.2,3 Our clinical trial was designed to test the very intervention that many women in our practice were beginning to adopt in the hopes of achieving relief from hot flushes, a complete soy beverage at a dose similar to traditional Asian diets. Furthermore, our intervention with soy was short-term and thus unlikely to pose an important risk, as even with prolonged use of estrogen therapy, the increase in incidence of breast cancer is modest and declines when hormones are stopped.4,5 It remains speculative if a short course of weak phytoestrogens, with no clinical evidence of an estrogenic effect greater than placebo as measured by hot flush relief, would result in a significant increase in risk of breast cancer. However, we are continuing long-term follow-up of the cohort of women who participated in this study to determine if soy beverage is associated with any excess risk of breast cancer recurrence or second breast primaries.The correspondent and others concerned about breast cancer risks from phytoestrogens are recommended to read a recent review article on the subject.3 The authors of that review conclude, "Overall, the data are not impressive that the adult consumption of soy affects the risk of developing breast cancer or that soy consumption affects the survival of breast cancer patients."1. Van Patten CL, Olivotto IA, Chambers K, et al: Effect of soy phytoestrogens on hot flashes in postmenopausal women with breast cancer: A randomized, controlled clinical trial. J Clin Oncol 20:: 1449,2002-1455, Link, Google Scholar2. Tham DM, Gardner CD, Haskell WL: Potential health benefits of dietary phytoestrogens: A review of the clinical, epidemiological, and mechanistic evidence. J Clin Endocrin Met 33:: 2223,1998-2235, Google Scholar3. Messina MJ, Loprinzi CL: Soy for breast cancer survivors: A critical review of the literature. J Nutr 131:: 3095S,2001-3108S, Crossref, Medline, Google Scholar4. Collaborative Group on Hormonal Factors in Breast Cancer: Breast cancer and hormone replacement therapy: Collaborative reanalysis of data from 51 epidemiological studies of 52,705 women with breast cancer and 108,411 women without breast cancer. Lancet 350:: 1047,1997-1059, Crossref, Medline, Google Scholar5. Collaborative Group on Hormonal Factors in Breast Cancer: Breast Cancer and hormonal contraceptives: Collaborative reanalysis of individual data on 53,297 women with breast cancer and 100,239 women without breast cancer from 54 epidemiological studies. Lancet 347:: 1713,1996-1727, Crossref, Medline, Google Scholar