Supplementary Material for: Patient Preferences for HR+/HER2‒ Early Breast Cancer Adjuvant Treatment: A Multicountry Discrete Choice Experiment

Introduction: More adjuvant treatment options are becoming available for hormone receptor–positive/human epidermal growth factor receptor 2–negative (HR+/HER2–) early breast cancer (EBC) based on results of clinical trials. This study quantified the importance of different attributes of EBC adjuvant therapies to patients and the benefit-risk tradeoffs patients were willing to make. Methods: Women with HR+/HER2– EBC completed an online discrete choice experiment (DCE) survey; the design was informed by clinical data, qualitative interviews (n=40), and pre-testing interviews (n=40). Participants (pts) made 10 choices between pairs of hypothetical treatments described by varying levels of 6 attributes. DCE data were analyzed using a correlated mixed logit model. Relative attribute importance scores captured the impact of each attribute across clinically relevant ranges. Benefit-risk tradeoffs were captured as the minimum improvements in 5-y invasive disease–free survival (iDFS) that pts would require to tolerate increases in therapy-associated adverse event (AE) risks. Results: A total of 866 patients from the US, France, Spain, Canada, the UK, Germany, South Korea, and Australia completed the DCE (mean age: 57.7 y; 76% postmenopausal; 29% stage I disease, 55% stage II, 16% stage III). Improved 5-y iDFS (75.4-82.7% range; associated with combination regimens [CRs] vs endocrine therapy [ET] alone) contributed the most to treatment preferences (clinically relevant relative attribute importance: 38.4%), followed by reduced risks of venous thromboembolic events (VTEs) (20.4%), neutropenia (20.3%), and diarrhea (15.0%). Treatment type + duration (3.7%) and fatigue (2.3%) were less important. Pts required the largest improvement in 5-y iDFS (3.9%) to tolerate increased risks of VTE (0.7% to 2.5%) or neutropenia (5.6% to 46%); willingness to accept tradeoffs depended on the AE. Preference heterogeneity was observed across subgroups, but 5-y iDFS improvement was consistently the most impactful on treatment choice in all subgroups. Conclusion: A multicountry sample of patients most valued adjuvant therapies with higher 5-y iDFS and may therefore prefer CRs over ET alone. The value of CRs depends on their specific safety profiles, and shared decision-making should consider this to select treatment options that align with individual preferences.