181 Background: In “window of opportunity” (WOO) clinical trials, people with newly diagnosed early-stage cancer are exposed to an experimental drug during the period of time between diagnosis and definitive anti-cancer treatment. These trials allow investigators to study drug efficacy in untreated disease, which can expedite drug development. However, for trial participants, the WOO approach requires them to decide about an altruistic clinical trial during an intense time immediately after cancer diagnosis. This qualitative study aimed to understand patient perspectives on WOO clinical trials. Methods: We recruited adults newly diagnosed with early-stage breast cancer who were awaiting definitive therapy at a single academic medical center. We developed an interview guide grounded in the theoretical framework, the Theory of Planned Behavior (TPB). TBP is a well-validated decision-making model with three domains that guide behavior: (1) attitudes (2) normative factors and (3) perceived difficulty of a behavior. We conducted one-on-one semi-structured interviews that were audio-recorded and transcribed. Transcripts were analyzed to ensure interrater reliability and content analysis was performed to assess themes that emerged. Results: We interviewed 15 women (age 32-72) with early-stage breast cancer, and the majority were White (n = 12, 80%) and at least college educated (n = 12, 80%). Key themes that emerged included favorable attitudes towards participating in a WOO trial that were altruistic, including the desire to contribute to science (n = 10, 67%) and to help future breast cancer patients (n = 5, 33%). Several individuals also identified a potential benefit to themselves (n = 10, 67%), including access to a targeted drug (n = 4, 27%) and adding meaning to their diagnosis (n = 3, 20%). However, most interviewees reported concerns about drug side effects (n = 12, 80%) and whether side effects would impact other planned treatments (n = 10, 67%). Interviewees also expressed family would be an important normative factor in decision-making (n = 8, 53%). A key theme that emerged as a difficulty was the potential delay in standard treatment (n = 14, 93%). Despite this concern, at the end of the interviews, most interviewees stated they would participate in a WOO trial if offered (n = 10, 67%). Conclusions: WOO trials are becoming increasingly common in oncology research. In this qualitative study, interviewees weighed altruism against the possibility delaying or impacting other treatments. Our results may inform trial design and communication approaches in future WOO efforts.

Purpose Window of opportunity trials (WOT) are increasingly common in oncology research. In WOT participants receive a drug between diagnosis and anti-cancer treatment, usually for the purpose of investigating that drugs effect on cancer biology. This qualitative study aimed to understand patient perspectives on WOT. Methods We recruited adults diagnosed with early-stage breast cancer awaiting definitive therapy at a single-academic medical center to participate in semi-structured interviews. Thematic and content analyses were performed to identify attitudes and factors that would influence decisions about WOT participation. Results We interviewed 25 women diagnosed with early-stage breast cancer. The most common positive attitudes toward trial participation were a desire to contribute to research and a hope for personal benefit, while the most common concerns were the potential for side effects and how they might impact fitness for planned treatment. Participants indicated family would be an important normative factor in decision-making and, during the COVID-19 pandemic, deemed the absence of family members during clinic visits a barrier to enrollment. Factors that could hinder participation included delay in standard treatment and the requirement for additional visits or procedures. Ultimately, most interviewees stated they would participate in a WOT if offered ( N = 17/25). Conclusion In this qualitative study, interviewees weighed altruism and hypothetical personal benefit against the possibility of side effect from a WOT. In-person family presence during trial discussion, challenging during COVID-19, was important for many. Our results may inform trial design and communication approaches in future window of opportunity efforts. Supplementary Information The online version contains supplementary material available at 10.1007/s10549-022-06611-6.