Preferences of women evaluating risks of tamoxifen (POWER) study of preferences for tamoxifen for breast cancer risk reduction

BACKGROUND. The objective of this study was to understand the attitudes and preferences of risk-eligible women regarding use of tamoxifen for breast cancer risk reduction. METHODS. A cross-sectional, mixed-methods interview study was conducted at a university medical center and at community sites. Participants were women who had an estimated 5-year breast cancer risk ≥ 1.7% and no prior breast cancer. Interviews were conducted in English or Spanish. The interview included a 15-minute, standardized educational session on the potential benefits and harms of tamoxifen followed by close-ended and open-ended questions about participants' inclinations to take tamoxifen and factors important to their decision. A demographic questionnaire, a test on knowledge of potential benefits and harms of tamoxifen, and an interview evaluation were included. RESULTS. Two hundred fifty-five women completed interviews. Their estimated mean 5-year breast cancer risk was 2.8%; and their mean self-perceived 5-year risk was 32.7%. After the educational intervention, 45 women (17.6%) were inclined to take tamoxifen. Very high risk women (> 3.5%) were no more inclined to take it than women with lower risk (1.7-3.5%). In a multivariable analysis, lower income, confidence in the effectiveness of tamoxifen, and concern about fractures were associated with being inclined to take it; concern about pulmonary embolism, dyspareunia, cataracts, and low self-perceived breast cancer risk were associated negatively with taking tamoxifen. Participants expressed concerns about adverse effects. CONCLUSIONS. Less than 20% of women were interested in tamoxifen after education about potential benefits and harms, despite a very high self-perceived breast cancer risk. Candidate chemoprevention agents must have few potential adverse effects to achieve widespread acceptance.