Researchers from the National Surgical Adjuvant Breast and Bowel Project (NSABP) who conducted the landmark Breast Cancer Prevention Trial (BCPT), report a seven-year and final update of the trial results in the November 16, 2005, Journal of the National Cancer Institute.
In this final report, reductions in breast cancer incidence among participants taking tamoxifen were found to be very similar compared to those reported in 1998 when initial findings from the BCPT were released. The conclusion is supported by the observation that the incidence rate of breast cancer was relatively constant through seven years of follow-up among women who received tamoxifen and by the fact that the rate remained stable for at least two years beyond the time that women stopped taking the drug. The risks of stroke, deep-vein thrombosis, and cataracts – possible side-effects of tamoxifen treatment – were also similar to those reported previously.
“The BCPT should be viewed not only as the first study that demonstrated that breast cancer can be prevented, but also as a beginning from which a new paradigm for breast cancer prevention can evolve,” said Bernard Fisher, M.D., first author of the initial and final reports, and principal investigator for the trial.
Cohorts of women at increased risk for breast cancer, who could derive a net benefit from receiving tamoxifen, have been clearly defined.
The BCPT was designed to see whether the drug tamoxifen could prevent breast cancer in women who were at an increased risk of developing the disease. Women in the study were randomly assigned to receive tamoxifen or a placebo, and neither participants nor their physicians were aware of the treatment assignment, a process called double-blinding. Since 1998, BCPT participants have been followed by the NSABP, the Pittsburgh-based research network that conducted the trial with support from the National Cancer Institute (NCI), part of the National Institutes of Health.