title: The aged breast.
abstract: There is a clear association between the development of breast cancer and increasing age, with 80% of cancers occurring in women more than 50 years of age and one-third in women over 70 years. Following the menopause the breast undergoes involution, with the main changes affecting the terminal ductal lobular unit. There is an increase in oestrogen receptor alpha (ERalpha)-positive cells, a decrease in proliferation but, in comparison to premenopausal breasts, a greater number of ERalpha-proliferating cells. The breast cancers that occur in women >/= 75 years are more likely to be ER-positive, with a low growth rate and limited expression of HER-2 and p53. It is proposed that uneven involution of the breast, the persistence of at-risk lesions, the presence of ERalpha-proliferating cells and local oestrogen metabolism in breast adipose tissue are factors in the development of breast cancers with a well-differentiated phenotype.
authors.affiliation: Breast Cancer Research Unit, Department of Cancer Studies and Molecular Medicine, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester Royal Infirmary, PO Box 65, Leicester LE2 7LX, UK. rawl4@le.ac.uk
authors.forename: R A
authors.initials: RA
authors.lastname: Walker
authors.forename: C V
authors.initials: CV
authors.lastname: Martin
mesh_terms: D000273:Adipose Tissue / Q000502:physiology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology / Q000502:physiology*; D001940:Breast / Q000473:pathology / Q000503:physiopathology*; D001943:Breast Neoplasms / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D002278:Carcinoma in Situ / Q000473:pathology / Q000503:physiopathology; D002455:Cell Division / Q000502:physiology; D047628:Estrogen Receptor alpha / Q000032:analysis; D005260:Female; D006801:Humans; D008875:Middle Aged; D009361:Neoplasm Invasiveness / Q000473:pathology / Q000503:physiopathology; D017698:Postmenopause / Q000502:physiology; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000032:analysis
chemical_list: D047628:Estrogen Receptor alpha; D018719:Erb-b2 Receptor Tyrosine Kinases