June 2025
Introduction: As the number of available treatment options for breast cancer increases, decision-making for patients has become complex. Patients often struggle to make decisions as treatment options can vary in terms of short- and long-term side effects, risks of recurrence, and impact on daily life.1 Numerous decision aids have been developed to support patient decision-making.2 However, sustained implementation and use of these tools remains limited. We propose that cognitive engineering approaches, such as naturalistic decision making (NDM), can provide a deeper understanding of how patients make treatment decisions, which can improve the design of decision support tools. Naturalistic decision making (NDM) is a theoretical perspective and methodological approach used to understand how people make decisions in the real world. Originally developed to understand decision-making of expert firefighters during crises, NDM approaches have been used to understand complex decision-making across domains including the military, offshore oil rigs, and healthcare.3,4 In this study, we used an NDM approach, the critical decision method (CDM), to gain an in-depth understanding of how breast cancer patients make treatment decisions following diagnosis. Methods: We conducted CDM interviews,5 with breast cancer patients diagnosis in the last 12 years. CDM interviews aim to understand critical or difficult events by unpacking the event using structured probes. One researcher conducted each interview over Zoom. We started each interview by asking the patient to reflect back on the beginning of their cancer journey and what they remember about their diagnosis. We then drew a timeline and asked the patient to relay the different treatments they considered or underwent for breast cancer. We then asked “Can you think of a time during your breast cancer journey when you had to make a difficult decision?” and probed patients about that decision. We continued asking patients about their treatment decision-making as time allowed. Each interview was audio-recorded and transcribed. A researcher and a patient advocate coded each interview and created a decision requirements table,6 which detailed the decisions made by the patient, what made that decision challenging, what strategies and information they used, and what their goals were at the time. We then met to discuss and come to consensus. Once a decision requirements table was created for each transcript, we developed aggregate tables and identified key themes. Results: We conducted 20 interviews, averaging 57 minutes each; patient age ranged from 42 to 81 years. Patients described an average of 8 decisions that they made following breast cancer diagnosis. Despite many patients facing the same decisions (e.g., mastectomy vs. lumpectomy), we found variability in which decisions were most difficult for patients. We identified 11 categories of difficult decisions for patients including whether to receive chemotherapy, getting genetic testing, stopping a medication due to side effects, and deciding where to receive treatment. Patients reported feeling time pressure and urgency to make treatment decisions and a fear of regretting their decisions. We found that patients’ firsthand experiences from friends who had cancer influenced their treatment decision-making. Given the heterogeneous nature of breast cancer treatment, this often presented a barrier to decision-making as patients expected to have the same experience and treatment options as their friends. Patients expressed variable goals when making treatment decisions, which often changed throughout their treatment journey. Conclusion: In this study, we explored how breast cancer patients made treatment decisions using NDM methods. This cognitive engineering approach revealed intricacies in the decision-making process of patients that will be valueable for improving the design of decision support tools. Next steps include collaborative design with patients to develop a tool that supports the broad spectrum of treatment decisions made across the patient journey. Citation Format: Megan Salwei, Barbara Voigtman, Janelle Faiman, Carrie Reale, Shilo Anders, Matthew Weinger. Harnessing Cognitive Engineering to Understand Breast Cancer Patient Decision Making [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2024; 2024 Dec 10-13; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(12 Suppl):Abstract nr P4-04-07.