Tamoxifen for the Prevention of Breast Cancer in High-Risk Women (IBIS-1)
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|ClinicalTrials.gov Identifier: NCT00002644|
Recruitment Status : Active, not recruiting
First Posted : May 11, 2004
Last Update Posted : February 26, 2019
|Condition or disease||Intervention/treatment||Phase|
|Breast Cancer||Drug: Tamoxifen Citrate 20Mg Tab Other: Placebo||Phase 3|
Established in 1992, the IBIS-I Study investigated the efficacy of tamoxifen (a hormonal drug used to prevent breast cancer) versus a placebo drug (taken daily for five years) in terms of reduction of breast cancer incidence in pre and postmenopausal women at high risk of developing breast cancer. It was a double-blind, randomised placebo-controlled trial that recruited 7,154 women internationally (of which 4,277 were UK participants), aged 35-70 years. The primary outcome measure was the incidence of breast cancer, including ductal carcinoma in situ (cancer cells in the lining of the breast milk duct) and side effects present in the patients were also investigated.
Recruitment to the study completed in 2001 and the intervention (placebo/tamoxifen) ended in 2007. In early 2008 the Research Ethics Committee (REC) approved the conversion of IBIS-I to an epidemiological cohort study. During 2007-2016 participants were followed-up via an annual postal questionnaire.
In 2002, initial results found that tamoxifen reduced the risk of invasive breast cancer by 31%. Mortality from non-breast cancer causes was not increased by tamoxifen. However, the analysis concluded that the overall risk/benefit ratio for the use of tamoxifen in prevention remained unclear and that continued follow-up of trial participants was essential. A 2007 analysis on long-term tamoxifen prophylaxis for breast cancer confirmed the preventive effect of tamoxifen in terms of breast cancer incidence and that this was constant for the entire follow-up period. No reduction in size of benefit was observed for up to ten years following participant randomisation. Additionally, tamoxifen-related side effects such as thrombo-embolism were not increased anymore after the 5-year treatment period. These results therefore demonstrate that the benefit-to-risk ratio of tamoxifen improves with increasing duration of follow-up. Thus, how much additional benefit will be seen long-term remains an important question.
|Study Type :||Interventional (Clinical Trial)|
|Actual Enrollment :||7154 participants|
|Intervention Model:||Parallel Assignment|
|Masking:||Triple (Participant, Care Provider, Investigator)|
|Official Title:||International Breast Cancer Intervention Study: A Multicentre Trial of Tamoxifen to Prevent Breast Cancer|
|Actual Study Start Date :||January 1994|
|Actual Primary Completion Date :||January 2001|
|Estimated Study Completion Date :||December 2024|
Experimental: Tamoxifen citrate
Tamoxifen citrate 20 mg/day for 5 years
Drug: Tamoxifen Citrate 20Mg Tab
Tamoxifen Citrate 20Mg Tab
Placebo Comparator: Placebo
Placebo 20 mg/day for 5 years
Placebo 20Mg Tab
To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT00002644
|Queen Mary University of London|
|London, England, United Kingdom, EC1M6BQ|
|Study Chair:||Jack Cuzick, PhD||Queen Mary University of London|