Purpose: To assess women’s preferences for breast cancer chemoprevention (i.e., tamoxifen or raloxifene) using conjoint analysis.
Methods: Eight attributes related to taking a pill to prevent breast cancer were identified and assigned levels (lifetime risk of breast cancer, length of time the pill must be taken, breast cancer risk reduction, risk of endometrial cancer, risk of blood clots, risk of hormone symptoms, risk reduction of bone fractures, and availability of a biomarker). The SAS conjoint analysis program was used to develop a balanced and efficient design consisting of 36 scenarios. Each scenario presented a hypothetical pill description, including each of the 8 attributes with different levels, and asked respondents to indicate how likely they would be to take that pill on a scale of 0 (not at all likely) to 9 (very likely). A randomized block design was used to equally divide the 36 scenarios. An Internet sample of women aged 40-74 was invited to complete one set of 18 scenarios plus a dominant scenario. The responses were combined and conjoint analysis was used to generate attribute importance scores and part-worth utilities of each level.
Results: The 1365 respondents had a mean age of 57 and 78% were white. The mean value for likelihood of taking the pill was 5.5 (SD 3.2) for the dominant scenario and ranged from 2.1 (SD 2.4)-5.7 (SD 2.4) for other scenarios. The order of attribute importance was lifetime risk (17.4%), time (17%), risk of blood clots (12.3%), risk of endometrial cancer (12%), breast cancer risk reduction (11.2%), biomarker availability (10.9%), reduction in bone fracture risk (9.7%) and risk of hormone symptoms (9.7%). Part-worth utility values indicated that women preferred a pill with the following features: 90% breast cancer risk reduction, had a biomarker, no additional risks for all side effects, and could be taken for 1 year.
Conclusions: There was low interest in taking a pill as a means of preventing breast cancer in this Internet sample even when the pill had high benefits and low risks. The similarity of attribute importance values suggests that all were somewhat important, with lifetime risk of breast cancer and serious, but rare, side effects being most important. Further research evaluating associations between preferences and chemoprevention adherence in high risk patients is needed.