Effects of low dose tamoxifen on normal breast tissue from premenopausal women

Eur J Cancer. 2003 May;39(7):891-8. doi: 10.1016/s0959-8049(02)00530-0.


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.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Adolescent
  • Adult
  • Antineoplastic Agents, Hormonal / administration & dosage*
  • Apoptosis
  • Biomarkers, Tumor / analysis*
  • Breast / chemistry
  • Breast / drug effects*
  • Breast Neoplasms / chemistry
  • Breast Neoplasms / drug therapy
  • Breast Neoplasms / pathology
  • Dose-Response Relationship, Drug
  • Double-Blind Method
  • Female
  • Fibroadenoma / drug therapy
  • Fibroadenoma / pathology
  • Humans
  • Immunohistochemistry
  • Ki-67 Antigen / metabolism
  • Mitosis
  • Premenopause
  • Receptors, Estrogen / metabolism
  • Receptors, Progesterone / metabolism
  • Tamoxifen / administration & dosage*


  • Antineoplastic Agents, Hormonal
  • Biomarkers, Tumor
  • Ki-67 Antigen
  • Receptors, Estrogen
  • Receptors, Progesterone
  • Tamoxifen