Phase III Randomized Adjuvant Study of Tamoxifen in Women With Early Breast Cancer. Note: The information about this trial has not been updated by the sponsor/principal investigator/lead organization. cannot verify the accuracy of the information.

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Alternate Title

Tamoxifen in Treating Women With Breast Cancer. Note: The information about this trial has not been updated by the sponsor/principal investigator/lead organization. cannot verify the accuracy of the information.

Basic Trial Information

PhaseTypeStatusAgeSponsorProtocol IDs
Phase IIITreatmentClosedNot specifiedOtherCRC-TU-ATTOM
EU-98042, ISRCTN17222211, NCT00003678


  1. Compare the disease-free and overall survival of women with early breast cancer who are randomized to discontinue adjuvant tamoxifen vs those randomized to continue for at least 5 additional years.

Entry Criteria

Disease Characteristics:

  • Histologically confirmed breast carcinoma that has been completely excised
    • Clinically relapse free
  • Must have completed at least two years of adjuvant therapy with tamoxifen for early breast cancer AND have no clear indication for or against receiving further tamoxifen
  • No significant endometrial hyperplasia
  • No patients with negligibly low risk of breast cancer death
  • Hormone receptor status:
    • Any status allowed

Prior/Concurrent Therapy:

    Biologic therapy:

  • Not specified


  • Not specified

    Endocrine therapy:

  • See Disease Characteristics


  • Not specified


  • See Disease Characteristics


  • Any primary treatment allowed

Patient Characteristics:


  • Not specified


  • Female

    Menopausal status:

  • Any status allowed

    Performance status:

  • Not specified

    Life expectancy:

  • Not specified


  • Not specified


  • Not specified


  • Not specified


  • No other life threatening disease
  • No retinopathy
  • No psychiatric disorder or other condition that would preclude study compliance
  • No serious toxicity (e.g., depression) thought to be due to tamoxifen
  • Not pregnant or nursing
  • Fertile patients must use effective contraception

Expected Enrollment


A total of 8,000-20,000 patients will be accrued for this study.


Primary Outcome(s)

All-cause mortality

Secondary Outcome(s)

Disease recurrence
Death due to breast cancer, other primary tumors, or cardiovascular causes


This is a randomized study. Patients are stratified for analysis according to duration of tamoxifen given before randomization (2-3 years vs 4-5 years vs 6-7 years vs 8-9 years vs 10 years and over), age (less than 49 vs over 50), and important prognostic factors, including tumor type and grade and nodal and estrogen receptor status. Patients are randomized to 1 of 2 treatment arms.

  • Arm I: Patients discontinue tamoxifen after at least 2 years of prior treatment.
  • Arm II: Patients continue treatment with tamoxifen for at least 5 additional years in the absence of unacceptable toxicity or disease progression.

Patients are followed annually.

Peer Reviewed and Funded or Endorsed by Cancer Research UK

Related Publications

Gray R, Davies C, Perry P: Tamoxifen for early breast cancer: better late than never. Ann Oncol 11 (5): 505-7, 2000.[PUBMED Abstract]

Rea D, Poole C, Gray R: Adjuvant tamoxifen: how long before we know how long? BMJ 316 (7143): 1518-9, 1998.[PUBMED Abstract]

Earl H, Gray R, Kerr D, et al.: The optimal duration of adjuvant tamoxifen treatment for breast cancer remains uncertain: randomize into aTTom. Clin Oncol (R Coll Radiol) 9 (3): 141-3, 1997.[PUBMED Abstract]

Earl H, Baker P, Kerr D, et al.: Adjuvant treatment with tamoxifen. Recruitment into studies assessing optimum duration of treatment must continue. BMJ 312 (7037): 1036-7, 1996.[PUBMED Abstract]

Gray R: Tamoxifen: how boldly to go where no women have gone before. J Natl Cancer Inst 85 (17): 1358-60, 1993.[PUBMED Abstract]

Trial Contact Information

Trial Lead Organizations

Queen Elizabeth Hospital at University Hospital of Birmingham NHS Trust

Daniel Rea, MD, Protocol chair
Ph: 44-121-472-1311

Registry Information

Official TitleA Large, Uniquely Simple, Randomised Study to Assess Much More Reliably the Balance of Benefits and Risks of Prolonging Adjuvant Tamoxifen Treatment in Early Breast Cancer
Trial Start Date1991-05-01
Registered in ClinicalTrials.govNCT00003678
Date Submitted to PDQ1998-11-18
Information Last Verified2007-03-26

Note: The purpose of most clinical trials listed in this database is to test new cancer treatments, or new methods of diagnosing, screening, or preventing cancer. Because all potentially harmful side effects are not known before a trial is conducted, dose and schedule modifications may be required for participants if they develop side effects from the treatment or test. The therapy or test described in this clinical trial is intended for use by clinical oncologists in carefully structured settings, and may not prove to be more effective than standard treatment. A responsible investigator associated with this clinical trial should be consulted before using this protocol.