Results of the ATAC (Arimidex, Tamoxifen, Alone or in Combination) Trial After Completion of 5 Years' Adjuvant Treatment for Breast Cancer

Lancet. 2005 Jan 1-7;365(9453):60-2. doi: 10.1016/S0140-6736(04)17666-6.

Abstract

The standard adjuvant endocrine treatment for postmenopausal women with hormone-receptor-positive localised breast cancer is 5 years of tamoxifen, but recurrences and side-effects restrict its usefulness. The aromatase inhibitor anastrozole was compared with tamoxifen for 5 years in 9366 postmenopausal women with localised breast cancer. After a median follow-up of 68 months, anastrozole significantly prolonged disease-free survival (575 events with anastrozole vs 651 with tamoxifen, hazard ratio 0.87, 95% CI 0.78-0.97, p=0.01) and time-to-recurrence (402 vs 498, 0.79, 0.70-0.90, p=0.0005), and significantly reduced distant metastases (324 vs 375, 0.86, 0.74-0.99, p=0.04) and contralateral breast cancers (35 vs 59, 42% reduction, 12-62, p=0.01). Almost all patients have completed their scheduled treatment, and fewer withdrawals occurred with anastrozole than with tamoxifen. Anastrozole was also associated with fewer side-effects than tamoxifen, especially gynaecological problems and vascular events, but arthralgia and fractures were increased. Anastrozole should be the preferred initial treatment for postmenopausal women with localised hormone-receptor-positive breast cancer.

Publication types

  • Comparative Study

MeSH terms

  • Anastrozole
  • Antineoplastic Agents, Hormonal / administration & dosage
  • Antineoplastic Agents, Hormonal / adverse effects
  • Antineoplastic Agents, Hormonal / therapeutic use*
  • Antineoplastic Combined Chemotherapy Protocols / adverse effects
  • Antineoplastic Combined Chemotherapy Protocols / therapeutic use
  • Aromatase Inhibitors / administration & dosage
  • Aromatase Inhibitors / adverse effects
  • Aromatase Inhibitors / therapeutic use*
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / mortality
  • Breast Neoplasms / pathology
  • Chemotherapy, Adjuvant
  • Disease-Free Survival
  • Estrogen Antagonists / administration & dosage
  • Estrogen Antagonists / adverse effects
  • Estrogen Antagonists / therapeutic use*
  • Female
  • Follow-Up Studies
  • Humans
  • Neoplasm Metastasis
  • Neoplasm Recurrence, Local
  • Nitriles / administration & dosage
  • Nitriles / adverse effects
  • Nitriles / therapeutic use*
  • Postmenopause
  • Randomized Controlled Trials as Topic
  • Survival Rate
  • Tamoxifen / administration & dosage
  • Tamoxifen / adverse effects
  • Tamoxifen / therapeutic use*
  • Triazoles / administration & dosage
  • Triazoles / adverse effects
  • Triazoles / therapeutic use*

Substances

  • Antineoplastic Agents, Hormonal
  • Aromatase Inhibitors
  • Estrogen Antagonists
  • Nitriles
  • Triazoles
  • Tamoxifen
  • Anastrozole