title: Phyto-oestrogens and breast cancer chemoprevention.
abstract: Phytoestrogens are polyphenol compounds of plant origin that exhibit a structural similarity to the mammalian steroid hormone 17beta-oestradiol. In Asian nations the staple consumption of phyto-oestrogen-rich foodstuffs correlates with a reduced incidence of breast cancer. Human dietary intervention trials have noted a direct relationship between phyto-oestrogen ingestion and a favourable hormonal profile associated with decreased breast cancer risk. However, these studies failed to ascertain the precise effect of dietary phyto-oestrogens on the proliferation of mammary tissue. Epidemiological and rodent studies crucially suggest that breast cancer chemoprevention by dietary phyto-oestrogen compounds is dependent on ingestion before puberty, when the mammary gland is relatively immature. Phyto-oestrogen supplements are commercially marketed for use by postmenopausal women as natural and safe alternatives to hormone replacement therapy. Of current concern is the effect of phyto-oestrogen compounds on the growth of pre-existing breast tumours. Data are contradictory, with cell culture studies reporting both the oestrogenic stimulation of oestrogen receptor-positive breast cancer cell lines and the antagonism of tamoxifen activity at physiological phyto-oestrogen concentrations. Conversely, phyto-oestrogen ingestion by rodents is associated with the development of less aggressive breast tumours with reduced metastatic potential. Despite the present ambiguity, current data do suggest a potential benefit from use of phyto-oestrogens in breast cancer chemoprevention and therapy. These aspects are discussed.
authors.affiliation: Molecular Medicine Unit, University of Leeds, St James's University Hospital, Leeds, UK.
authors.forename: Jane L
authors.initials: JL
authors.lastname: Limer
authors.forename: Valerie
authors.initials: V
authors.lastname: Speirs
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000818:Animals; D016588:Anticarcinogenic Agents / Q000737:chemistry / Q000494:pharmacology / Q000627:therapeutic use*; D018931:Antineoplastic Agents, Hormonal / Q000037:antagonists & inhibitors / Q000627:therapeutic use; D001208:Asia / Q000453:epidemiology / Q000208:ethnology; D001943:Breast Neoplasms / Q000188:drug therapy / Q000453:epidemiology / Q000517:prevention & control*; D002648:Child; D004641:Emigration and Immigration; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology / Q000627:therapeutic use*; D004967:Estrogens; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D007223:Infant; D007529:Isoflavones / Q000009:adverse effects / Q000737:chemistry / Q000494:pharmacology / Q000627:therapeutic use*; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced / Q000517:prevention & control; D051379:Mice; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors; D009376:Neoplasms, Hormone-Dependent / Q000188:drug therapy / Q000517:prevention & control; D048789:Phytoestrogens; D028321:Plant Preparations / Q000009:adverse effects / Q000737:chemistry / Q000494:pharmacology / Q000627:therapeutic use*; D017698:Postmenopause; D017697:Premenopause; D015995:Prevalence; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011960:Receptors, Estrogen / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013329:Structure-Activity Relationship; D014481:United States / Q000453:epidemiology
chemical_list: D016588:Anticarcinogenic Agents; D018931:Antineoplastic Agents, Hormonal; D004791:Enzyme Inhibitors; D004967:Estrogens; D007529:Isoflavones; D009363:Neoplasm Proteins; D048789:Phytoestrogens; D028321:Plant Preparations; D011960:Receptors, Estrogen; D011505:Protein-Tyrosine Kinases