Implications for Chemoprevention

Background:Somewomenmaybenefitfromtakingtamoxifen citrate for breast cancer prevention if the probability of benefit outweighs that of adverse events. We determinedtheproportionofwomenaged40to69years attending general internal medicine practices who were potentially eligible for tamoxifen chemoprevention and calculatedthemaximumproportionofbreastcancersthat could be prevented. Methods: Six hundred five women aged 40 to 69 completed self-administered questionnaires in the waiting roomsof10generalinternalmedicinepracticesinNorth Carolina in 2001. Results: Among white women, 9.0% (95% confidence interval [CI], 5.1%-15.2%) in their 40s, 24.0% (95% CI, 18.2%-31.0%) in their 50s, and 53.4% (95% CI, 46.1%61.3%) in their 60s had a 5-year Gail model estimated breast cancer risk of 1.66% or greater. Among black women,2.9%(95%CI,0%-15.0%)intheir40s,7.1%(95% CI, 1.1%-24.4%) in their 50s, and 13.0% (95% CI, 3.1%34.3%)intheir60shadasimilarrisk.Whenadverseevents wereconsideredinwhitewomen,10%orfewerinallage groupswerepotentiallyeligibleforchemoprevention.The maximum proportion of breast cancers prevented in eligible women was 6.0% to 8.3%. Conclusions:Small numbers of women in primary care practices are eligible for discussions about chemoprevention; the maximum proportion of breast cancers prevented if eligible women take tamoxifen is also small. Challenges lie in targeting discussions to the most appropriate women and in finding new chemoprevention strategies that have less risk of harms. Arch Intern Med. 2004;164:1897-1903