Tamoxifen Study

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00000529
Recruitment Status : Completed
First Posted : October 28, 1999
Last Update Posted : November 2, 2016
National Cancer Institute (NCI)
Information provided by:
National Heart, Lung, and Blood Institute (NHLBI)

Brief Summary:
To assess the impact of tamoxifen on development of breast cancer, coronary heart disease, and bone fractures. The National Cancer Institute initiated the prevention trial under its National Surgical Adjuvant Breast and Bowel Project (NSABP). The National Heart, Lung, and Blood Institute provided support to obtain blood pressure and lipid measurements, and lipoprotein and selected coagulation factor measurements in a subsample.

Condition or disease Intervention/treatment Phase
Cardiovascular Diseases Coronary Disease Heart Diseases Hypertension Myocardial Ischemia Drug: tamoxifen Phase 3

Detailed Description:


Tamoxifen is nominally called an 'anti-estrogen' although it has some estrogen-agonist activities and tends to increase plasma endogenous estrogen levels. Several studies have confirmed that it decreases plasma total cholesterol and LDL-cholesterol and a review of mortality in patients taking tamoxifen as adjuvant therapy for breast cancer indicates a decreased number of vascular deaths in women on tamoxifen compared to those not on this agent.


Subjects were randomized to receive 10 mg of tamoxifen two times a day or to placebo. The primary endpoint was prevention of invasive breast cancer. The secondary endpoint was the effects on fatal and nonfatal cardiovascular events (coronary heart disease, stroke, and thromboembolic disease) and fractures. A total of 13,388 women at increased risk for breast cancer were randomly assigned to receive either tamoxifen (20 milligrams per day) or placebo. Cardiovascular follow-up was available for 13,194 women. The median follow-up was 57 months; the mean follow-up was 49 months. During long-term follow-up, 76 percent of the tamoxifen participants were compliant with the study therapy; 83 percent were compliant through 24 months of follow-up. To evaluate the effects of tamoxifen in women with and without pre-existing heart disease, the 13,388 women enrolled at the 131 clinical sites were divided into subgroups of those with and without a self-reported history of clinical coronary heart disease, defined as myocardial infarction or angina prior to randomization. Medical records for subjects with suspected cardiovascular events were collected by the clinical sites and forwarded to the NSABP Operations Center for adjudication by investigators who were blinded to treatment assignment. Primary cardiovascular events included fatal myocardial infarction, Q-wave myocardial infarction, and non-Q-wave myocardial infarction. Secondary cardiovascular events included unstable angina (angina requiring hospitalization) and severe angina (angina requiring revascularization). All subjects were included in the analysis using the intent-to-treat principle.

Study Type : Interventional  (Clinical Trial)
Allocation: Randomized
Primary Purpose: Prevention
Study Start Date : May 1992
Study Completion Date : November 1995

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Ages Eligible for Study:   35 Years to 75 Years   (Adult, Older Adult)
Sexes Eligible for Study:   Female
Accepts Healthy Volunteers:   No
Women over the age of 35 with a 5-year predicted breast cancer risk of at least 1.66 percent or a history of lobular breast carcinoma in situ, life expectancy of 10 years or more, breast examination and mammogram without evidence of cancer, no hormonal therapy within three months prior to randomization, and no history of deep venous thrombosis or pulmonary embolism. .

Publications: Identifier: NCT00000529     History of Changes
Other Study ID Numbers: 72
First Posted: October 28, 1999    Key Record Dates
Last Update Posted: November 2, 2016
Last Verified: August 2001

Additional relevant MeSH terms:
Cardiovascular Diseases
Heart Diseases
Coronary Disease
Coronary Artery Disease
Myocardial Ischemia
Pathologic Processes
Vascular Diseases
Arterial Occlusive Diseases
Estrogen Antagonists
Hormone Antagonists
Hormones, Hormone Substitutes, and Hormone Antagonists
Physiological Effects of Drugs
Antineoplastic Agents, Hormonal
Antineoplastic Agents
Selective Estrogen Receptor Modulators
Estrogen Receptor Modulators
Bone Density Conservation Agents