ABSTRACT
BACKGROUND: There is substantial nonadherence to effective adjuvant endocrine therapy for breast cancer prevention. We therefore examined patients' trade-offs between the efficacy, side-effects, and regimen duration, and whether trade-offs predicted nonadherence. PATIENTS AND METHODS: Trade-offs from 241 women were assessed with an Adaptive Conjoint Analysis (ACA) choice task that was customized to each individual patient. From the estimated ACA utilities, the relative importance of each treatment property was calculated and a benefit/drawback ratio between the importance of the efficacy versus that of the side-effects and other treatment properties. Nonadherence was assessed through composites of validated self-report measures. RESULTS: Efficacy was most important. The side-effects joint and muscle pain and risk of endometrial cancer were almost as important. The benefit/drawback ratio showed 16% of the women to value the efficacy less than the side-effects and other treatment properties. A higher benefit/drawback ratio was associated with decreased nonadherence [adjusted odds ratio (OR) 0.1, 95% confidence interval 0.03-0.3]. CONCLUSIONS: One in six women do not consider the efficacy of endocrine therapy to outweigh its drawbacks. Knowing women's trade-offs is likely to identify women at risk for nonadherence and to help clinicians in tailoring their communication and care to different needs of individual women.