How might participants use of estrogen hormone replacement therapy affect the findings of the European studies?
Tamoxifen can interact with the same receptor on cells that binds estrogen.Consequently, there is a theoretical possibility that estrogen use may block the effect of tamoxifen. In the two European studies, 14 percent or 42 percent of the participants were taking estrogen. In the BCPT, the use of estrogen was not permitted so that the effect of tamoxifen alone could be evaluated. VIII. Were the BCPT results released too early? No. An integral part of the BCPT was an independent Endpoint Review, Safety Monitoring, and Advisory Committee. At its regularly scheduled meeting in March of 1998, this committee concluded that the BCPT’s primary question-whether tamoxifen can prevent breast cancer in women at greater-than-average risk-had been answered. It was concluded that the value of additional information that might be gained from continuing the study did not outweigh the benefits of making tamoxifen available to the participants in the placebo group and other women at increased risk of bre
