title: Effects of low dose tamoxifen on normal breast tissue from premenopausal women.
abstract: The aim of this study was to determine the effects of low doses of tamoxifen (5 and 10mg/day) for 50 days compared with the standard dose (20 mg/day) on breast biomarkers measured in normal breast tissue from premenopausal patients. A randomised double-blind study was performed using tissue from 56 premenopausal women with a diagnosis of fibroadenoma of the breast. Excisional biopsy was performed on the 50th day of therapy. Normal breast tissue samples were collected during surgery. The patients were divided in groups: A (placebo, n=11); group B (5 mg, n=16), group C (10 mg, n=14) and group D (20 mg, n=15). In this cross-sectional study, differences in the expression of Oestrogen Receptor alpha (ERalpha), Progesterone Receptor (PR), Ki-67, apoptotic bodies and mitotic index between the different groups after treatment can be seen on the normal breast tissue. We believe that a lower dose of tamoxifen could reduce the side-effects associated with treatment without affecting its chemopreventive activity in the breast.
authors.affiliation: Department of Gynecology, Federal University of São Paulo (UNIFESP), São Paulo, Brazil.
authors.forename: G R
authors.initials: GR
authors.lastname: de Lima
authors.forename: G
authors.initials: G
authors.lastname: Facina
authors.forename: J Y
authors.initials: JY
authors.lastname: Shida
authors.forename: M B C
authors.initials: MB
authors.lastname: Chein
authors.forename: P
authors.initials: P
authors.lastname: Tanaka
authors.forename: R C
authors.initials: RC
authors.lastname: Dardes
authors.forename: V C
authors.initials: VC
authors.lastname: Jordan
authors.forename: L H
authors.initials: LH
authors.lastname: Gebrim
mesh_terms: D000293:Adolescent; D000328:Adult; D018931:Antineoplastic Agents, Hormonal / Q000008:administration & dosage*; D017209:Apoptosis; D014408:Biomarkers, Tumor / Q000032:analysis*; D001940:Breast / Q000737:chemistry / Q000187:drug effects*; D001943:Breast Neoplasms / Q000737:chemistry / Q000188:drug therapy / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D018226:Fibroadenoma / Q000188:drug therapy / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000378:metabolism; D008938:Mitosis; D017697:Premenopause; D011960:Receptors, Estrogen / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism; D013629:Tamoxifen / Q000008:administration & dosage*
chemical_list: D018931:Antineoplastic Agents, Hormonal; D014408:Biomarkers, Tumor; D019394:Ki-67 Antigen; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D013629:Tamoxifen