title: It's time for clinicians to reconsider their proscription against the use of soyfoods by breast cancer patients.
abstract: The impact of soyfood intake on breast cancer risk has been intensely investigated. This focus can be attributed to soyfoods being uniquely rich dietary sources of isoflavones. Isoflavones are classified as both phytoestrogens and selective estrogen receptor (ER) modulators. The finding that dietary genistein, the primary soybean isoflavone, stimulates the growth of existing mammary tumors in ovariectomized athymic mice implanted with ER-positive breast cancer cells has led many oncologists to advise their patients against the use of soyfoods. However, the clinical evidence indicates that isoflavone exposure has little effect on markers of breast cancer risk. Furthermore, a pooled analysis that involved 9,514 breast cancer survivors found higher isoflavone intake was associated with a statistically significant 25% reduction in recurrence over the average 7.4-year follow-up period. Given the clinical and epidemiologic data, our position is that clinicians should allow soyfood use by patients for whom soyfoods already represent a normal part of their diet, and should not discourage other breast cancer survivors from moderate consumption.
authors.affiliation: Department of Nutrition, School of Public Health, Loma Linda University, Loma Linda, California.
authors.forename: Mark
authors.initials: M
authors.lastname: Messina
authors.forename: Bette J
authors.initials: BJ
authors.lastname: Caan
authors.forename: Donald I
authors.initials: DI
authors.lastname: Abrams
authors.forename: Mary
authors.initials: M
authors.lastname: Hardy
authors.forename: Gertraud
authors.initials: G
authors.lastname: Maskarinec
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000517:prevention & control*; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D004032:Diet; D004847:Epithelial Cells / Q000378:metabolism; D005260:Female; D019833:Genistein / Q000627:therapeutic use; D006728:Hormones / Q000378:metabolism; D006801:Humans; D007529:Isoflavones / Q000627:therapeutic use*; D061986:MCF-7 Cells; D008327:Mammography; D051379:Mice; D009558:Nipples / Q000378:metabolism; D048789:Phytoestrogens / Q000627:therapeutic use; D045730:Soy Foods
chemical_list: D006728:Hormones; D007529:Isoflavones; D048789:Phytoestrogens; D019833:Genistein