Abstract PS5-05-08: Physician perspectives on treatment decision-making process in high-risk early-stage triple negative breast cancer (esTNBC) in a community oncology setting

Abstract Background: Pembrolizumab, approved by the FDA in July 2021, is a standard of care (SOC) for neoadjuvant treatment of high-risk esTNBC, based on effectiveness established in the KEYNOTE-522 trial. Understanding factors affecting clinical integration are now critical to optimize patient outcomes. This study explored physician perspectives on pembrolizumab use in neoadjuvant and adjuvant settings and treatment decision-making process for high-risk esTNBC. Methods: In January 2025, physicians from The US Oncology Network completed a brief online survey and a virtual focus group discussion. Physicians were chosen for their TNBC management experience and geographical diversity. Survey data were analyzed quantitatively, while the discussion was transcribed and key themes identified qualitatively. Results: Six medical oncologists and two breast surgeons completed the survey and focus group discussion. SOC adoption The discussion revealed that the implementation of pembrolizumab is primarily driven by its status as the SOC, potential to enhance patient survival, and manageable side effect profile. On the survey, physicians estimated they use neoadjuvant pembrolizumab plus chemotherapy in 90% -100% of their esTNBC patients. Rare exceptions for non-use Focus group physicians reported rare exceptions to pembrolizumab as SOC. These include patients with immunotherapy contraindications, like severe autoimmune diseases or kidney transplants. Patients usually adhere to medical advice but occasionally, some patients decline neoadjuvant or adjuvant therapy due to side effect concerns or fear of progression and prefer immediate surgery. Additionally, focus group physicians reported that occasionally patients are referred post-surgery by general surgeons without having received neoadjuvant therapy. In other instances, focus group physicians indicated that patients with low disease burden, inoperable tumors, or urgent surgical needs may also not receive pembrolizumab. Treatment of ER-Low Breast Cancer All focus group physicians reported treating breast cancer patients with ER-low (1% - 9%) status similarly to TNBC patients. Extensive adjuvant use Seven surveyed physicians described that they use adjuvant pembrolizumab in >75% of their esTNBC patients who achieve pCR. However, patient-specific contraindications and clinician concerns for toxicity remain barriers to its recommendation as reported by five and four surveyed physicians, respectively. Conclusions: This qualitative study of breast cancer physicians reveals broad adoption of pembrolizumab as SOC for high-risk esTNBC in The US Oncology Network, due to survival benefits and tolerable side effects. Usage is limited by comorbidities, patient preferences, and post-surgery referrals. Future efforts are essential to guide improvements in patient communication, enhance surgeon awareness on current neoadjuvant guidelines, shared decision-making, and multidisciplinary care coordination, ultimately optimizing patient outcomes. Citation Format: A. Haiderali, L. Okoth, S. Annavarapu, J. K. Paulus, W. Pan, P. Conkling, M. Danso. Physician perspectives on treatment decision-making process in high-risk early-stage triple negative breast cancer (esTNBC) in a community oncology setting [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS5-05-08.