Willingness of Women with Early Estrogen Receptor–Positive Breast Cancer to Take Adjuvant CDK4/6 Inhibitors

Background: The steady decline in breast cancer (bca) mortality has come at the cost of increasingly toxic and expensive adjuvant therapies. Trials evaluating the addition of 2 or 3 years of cyclin-dependent kinase 4/6 (cdk4/6) inhibitors to adjuvant endocrine therapy (et) are ongoing, but the willingness of patients to take such additional therapy is unknown. Methods: We surveyed 100 consecutive postmenopausal women with nonmetastatic estrogen receptor–positive bca who had initiated adjuvant et within the preceding 2 years. Participants were asked about perceived recurrence risk, bca worry, and overall health. They were then asked about their willingness to accept 2 years of treatment with an additional oral drug that would reduce recurrence by 40% for a range of baseline recurrence risks in 2 hypothetical scenarios. Results: Mean age of the 99 evaluable participants was 61.7 years. In the scenario with no drug toxicity, 85% of respondents were likely to accept the new drug for a reduction in recurrence to 30% from 50%, but only 49% would take the drug if risk was reduced to 3% from 5%. In a scenario with drug-induced fatigue, the corresponding drug acceptance rates were 55% and 39% respectively. For the second scenario, bca worry was correlated with increased willingness to take the drug, even for only a 2% absolute reduction in recurrence risk. Conclusions: The willingness of patients with estrogen receptor–positive bca to take an adjuvant cdk4/6 inhibitor will greatly depend on the expected benefit and toxicities described to them as well as on worry about bca recurrence.