Fulvestrant, an estrogen receptor downregulator, reduces cell turnover index more effectively than tamoxifen

Anticancer Res. Jul-Aug 2002;22(4):2317-9.


Background: This study was performed to determine whether drug action on breast tumours could also be analysed using a cell turnover index (CTI), a composite measurement of both proliferation and apoptosis.

Materials and methods: Data were obtained from a randomized, placebo-controlled trial comparing three single doses (50, 125 and 250 mg) of intramuscular fulvestrant (Faslodex, previously known as ICI 182,780) with oral tamoxifen 20 mg/day for 14-21 days in women with early, operable, ER-positive breast cancer. CTI was calculated as the ratio of the proliferation index to the apoptotic index.

Results: Fulvestrant 250 mg significantly reduced CTI compared with both placebo (p = 0.0003) and tamoxifen (p = 0.026). The effect on CTI with tamoxifen was not significantly different from that with placebo.

Conclusion: This study suggests that CTI may be a useful indicator of drug action on breast tumour growth. A significant reduction in growth was found with fulvestrant 250 mg compared with tamoxifen.

Publication types

  • Clinical Trial
  • Comparative Study
  • Multicenter Study
  • Randomized Controlled Trial

MeSH terms

  • Antineoplastic Agents / pharmacology*
  • Apoptosis / drug effects
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / pathology*
  • Cell Division / drug effects*
  • Estradiol / analogs & derivatives
  • Estradiol / therapeutic use*
  • Estrogen Receptor Modulators / pharmacology*
  • Female
  • Fulvestrant
  • Humans
  • Ki-67 Antigen / analysis
  • Kinetics
  • Placebos
  • Tamoxifen / pharmacology*
  • Tumor Cells, Cultured


  • Antineoplastic Agents
  • Estrogen Receptor Modulators
  • Ki-67 Antigen
  • Placebos
  • Tamoxifen
  • Fulvestrant
  • Estradiol