Tamoxifen as a Preventive Agent for Invasive Breast Cancer

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Alternate Title

Randomized, Placebo-Controlled Clinical Trial to Determine the Worth of Tamoxifen for Preventing Breast Cancer

Basic Trial Information

PhaseTypeStatusAgeSponsorProtocol IDs
No phase specifiedPreventionCompleted35 and overNCINSABP-P-1
BCPT-1, NSABP P-1, NCI-P91-0022

Trial Description


Estrogen can stimulate the growth of breast cancer cells. Hormone therapy using tamoxifen may fight breast cancer by reducing the production of estrogen.

Trial to study the effectiveness of tamoxifen in preventing invasive breast cancer, in reducing breast cancer deaths in women at increased risk, and in reducing broken bones and deaths caused by heart disease in these women.


  • 35-59 years old
  • No previous history of invasive breast cancer
  • At increased risk for developing breast cancer
  • No other serious medical problems
  • For more information about the eligibility criteria for this trial, refer to the Health Professional version.

Final eligibility for a clinical trial is determined by the health professionals conducting the trial.


Participants will be randomized to one of two groups: those taking tamoxifen by mouth once a day for 5 years; or those taking a placebo by mouth once a day for 5 years.


For more details about this trial, refer to the Health Professional version of the trial summary.

If you are interested in participating in a clinical trial, contact your doctor for a referral or call a trial contact person listed below. You may see the same contact person listed at more than one site, however, if you call the number listed you can ask to speak to the study coordinator or person involved with the specific trial you are interested in. If you have questions about cancer or clinical trials, call the Cancer Information Service at 1-800-4-CANCER (1-800-422-6237). General information about clinical trials, including risks, benefits, and costs, can be found on NCI's Web site.

Trial Contact Information

Trial Lead Organizations

National Surgical Adjuvant Breast and Bowel Project

Norman Wolmark, MD, Protocol chair
Ph: 412-359-3336; 866-680-0004