The pre-operative window of endocrine therapy to inform radiation therapy decisions (POWER) trial: Baseline patient beliefs about breast cancer and endocrine therapy.

Abstract

11115 Background: The POWER Trial (NCT04272801) aims to determine whether pre-operative endocrine therapy (pre-ET) impacts physician recommendations and patient preferences for adjuvant radiation (RT) and endocrine therapy (AET) among women who qualify for RT omission. While physicians characterize this population as low-risk, they often still recommend RT. The POWER trial captures baseline patient perspectives regarding recurrence and medication tolerance using patient-reported outcome surveys and examines how these influence treatment choices. Methods: POWER Trial participants received 90 days of pre-ET before surgery and treatment decisions regarding RT. Women ≥ 65 years old with ER+ tumors ≤ 2 cm, node negative were eligible. Patient beliefs about their cancer and medications were assessed at baseline using the Beliefs About Illness Questionnaire (BIP-Q), Beliefs About Medicine Questionnaire-ET (BMQ-ET), and Perceived Sensitivity to Medicines (PSM) scale. An additional novel, non-validated questionnaire was created to further evaluate patients’ beliefs. Results: The study cohort included 48 women with mean age of 73.7. Few patients (14.6%) viewed their breast cancer as having a high threat to their health. While half (50.0%) of the participants worried a lot about the return of their breast cancer, only 35.4% thought that a cancer recurrence would be devastating. Participants who worried more about their breast cancer returning were more likely to feel a recurrence would be devastating (Pearson Correlation Coefficient = .67). There was no association between baseline beliefs and RT omission. Most patients (81.3%) did not consider themselves sensitive to medications. Although 81.3% reported side effects as important when deciding to continue or stop medications, almost all participants (95.8%) stated they would continue medications, despite side effects, if it would help lower their risk of recurrence. When specifically asked about AET, 70.8% reported a low level of concern about taking the therapy and 72.9% felt it was necessary. Of study participants, 27 (56.3%) omitted RT and initiated AET, 10 (20.8%) had RT and declined AET, 10 (20.8%) completed RT and initiated AET, and 1 (2.1%) declined RT and AET. Conclusions: This analysis shows that many early-stage ER+ breast cancer patients have a low level of worry about breast cancer recurrence, which may support treatment de-escalation such as RT omission. Most participants are open to taking AET despite the potential for side effects, yet historical data demonstrate low rates of adherence to AET. This discrepancy highlights that patients’ baseline beliefs about themselves and their medications may not align with their actual adherence. Future analysis from the POWER trial will examine how long-term AET adherence relates to baseline patient beliefs. Clinical trial information: NCT04272801 .