Anastrozole is superior to tamoxifen as first-line therapy in hormone receptor positive advanced breast carcinoma

Cancer. 2001 Nov 1;92(9):2247-58. doi: 10.1002/1097-0142(20011101)92:9<2247::aid-cncr1570>;2-y.


Background: Two randomized, double-blind trials have compared tamoxifen 20 mg daily and the selective, nonsteroidal aromatase inhibitor anastrozole 1 mg daily as first-line therapy for advanced breast carcinoma (ABC) in postmenopausal women. The trials were prospectively designed to allow for combined data analyses.

Methods: The combined study population included 1021 postmenopausal women (median age, 67 years [range, 30-92]) with ABC whose tumors were either estrogen and/or progesterone receptor positive or of unknown receptor status. Primary endpoints were time to progression (TTP), objective response, and tolerability.

Results: At a median duration of follow-up of 18.2 months, anastrozole was at least equivalent to tamoxifen in terms of median TTP (8.5 and 7.0 months, respectively; estimated hazard ratio [tamoxifen relative to anastrozole], 1.13 [lower 95% confidence level, 1.00]). In a retrospective subgroup analysis, anastrozole was superior to tamoxifen with respect to TTP (median values of 10.7 and 6.4 months for anastrozole and tamoxifen, respectively, two-sided P = 0.022) in patients with estrogen and/or progesterone receptor positive tumors (60% of combined trial population). In terms of objective response, 29.0% of anastrozole and 27.1% of tamoxifen patients achieved either a complete response (CR) or a partial response (PR). Clinical benefit (CR + PR + stabilization of > or = 24 weeks) rates were 57.1% and 52.0% for anastrozole and tamoxifen, respectively. Both anastrozole and tamoxifen were well tolerated. Anastrozole led to significantly fewer venous thromboembolic (P = 0.043; not adjusted for multiple comparisons) events, and vaginal bleeding was reported in fewer patients treated with anastrozole than with tamoxifen.

Conclusions: In postmenopausal women with hormonally sensitive ABC, anastrozole should be considered as the new standard first-line treatment.

Publication types

  • Clinical Trial
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Anastrozole
  • Antineoplastic Agents, Hormonal / pharmacology*
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / pathology
  • Double-Blind Method
  • Female
  • Hemorrhage / chemically induced
  • Humans
  • Middle Aged
  • Nitriles / pharmacology*
  • Postmenopause
  • Prognosis
  • Receptors, Estrogen / analysis*
  • Receptors, Progesterone / analysis*
  • Survival Analysis
  • Tamoxifen / pharmacology*
  • Thromboembolism / chemically induced
  • Treatment Outcome
  • Triazoles / pharmacology*


  • Antineoplastic Agents, Hormonal
  • Nitriles
  • Receptors, Estrogen
  • Receptors, Progesterone
  • Triazoles
  • Tamoxifen
  • Anastrozole