title: Effects of soy isoflavone and endogenous oestrogen on breast cancer in MMTV-erbB2 transgenic mice.
abstract: OBJECTIVE
  Soy isoflavone is associated with modification of breast cancer risk. Effects of dietary isoflavone on breast tissue carcinogenesis under varying endogenous oestrogen contexts were investigated.
  
  
  METHODS
  Five-week-old mouse mammary tumour virus (MMTV)-erbB2 female transgenic  mice (n = 180) were divided into three equal groups: low-, normal- and high-oestrogen groups. Each group was then subdivided into an experimental group (given soybean feed) and a control group (given control feed).
  
  
  RESULTS
  In the high-oestrogen environment, breast cancer incidence  was significantly lower in the experimental versus the control group, whereas in the low-oestrogen environment, breast cancer incidence was significantly higher in the experimental versus the control group. There were no between-group differences in mean breast tumour latency, mean largest  tumour diameter and breast tumour tissue vascular endothelial growth factor levels.
  
  
  CONCLUSIONS
  Dietary soy isoflavones promote breast cancer at low oestrogen levels but inhibit breast cancer at high oestrogen levels. This effect may only occur during the initiation stage of breast cancer.
authors: Department of Oncology, Cancer Institute, First Affiliated Hospital of Henan University of Science and Technology, Luoyang, China.
authors: G P
authors: GP
authors: Zhang
authors: D
authors: D
authors: Han
authors: G
authors: G
authors: Liu
authors: S G
authors: SG
authors: Gao
authors: X Q
authors: XQ
authors: Cai
authors: R H
authors: RH
authors: Duan
authors: X S
authors: XS
authors: Feng
mesh_terms: D000818:Animals; D004032:Diet; D004967:Estrogens / Q000378:metabolism / Q000494:pharmacology*; D005260:Female; D018734:Genes, erbB-2 / Q000235:genetics*; D007529:Isoflavones / Q000008:administration & dosage / Q000494:pharmacology*; D015674:Mammary Neoplasms, Animal / Q000178:diet therapy* / Q000821:virology; D008324:Mammary Tumor Virus, Mouse / Q000187:drug effects / Q000235:genetics*; D051379:Mice; D008822:Mice, Transgenic; D010052:Ovariectomy; D030262:Soybean Proteins / Q000494:pharmacology; D013025:Glycine max; D042461:Vascular Endothelial Growth Factor A / Q000032:analysis
chemical_list: D004967:Estrogens; D007529:Isoflavones; D030262:Soybean Proteins; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse