Long-Term Benefit of Tamoxifen Chemoprevention

The risk for developing breast cancer was reduced for more than a decade after 5 years of treatment.

The prior International Breast Cancer Intervention Study I (IBIS-I) showed that, after a median follow-up of 8 years, tamoxifen reduced the risk for estrogen receptor (ER)-positive breast cancer in women at high risk for developing breast cancer (NEJM JW Oncol Hematol Mar 12 2007). Despite this finding and similar results from other large randomized trials, the adoption of tamoxifen in this population has remained very low.

Now, investigators report longer-term results of the IBIS-I study, which involved 7154 women (ages 35–70) with a ≥2-fold risk for developing breast cancer who were randomized to 5 years of tamoxifen or placebo. Hormone replacement therapy (HRT) was received by 40.5% of patients in the tamoxifen group and by 49.5% in the p…

Reviewing Author

William J. Gradishar, MD

Disclosures

Consultant/Advisory BoardLilly; AstraZeneca; Gilead

Grant/Research SupportBreast Cancer Research Foundation

Editorial BoardsClinical Breast Cancer; Oncology; Annals of Surgery; Breast Cancer Research and Treatment

Leadership Positions in Professional SocietiesNational Comprehensive Cancer Network (Chair, Breast Cancer Panel); American Board of Internal Medicine (Medical Oncology Board)