Abstract PS5-12-02: Quantifying the value of progression-free survival in breast cancer treatment among a general population of US women

Abstract Background: While progression-free survival (PFS) often serves as a surrogate endpoint in metastatic breast cancer (mBC) treatment approvals, it is unclear whether patients prefer PFS to overall survival (OS), or whether patients are willing to accept greater uncertainty in OS in exchange for more immediate PFS gains. Methods: A nationwide survey was administered to US women aged ≥ 21 years. The survey asked respondents to imagine they were a mBC patient choosing between two hypothetical mBC treatment options (Table): a “certain OS” option (PFS=5.5 months, OS=24 months) versus an “uncertain OS” option defined as having higher PFS (8 months) and uncertain OS with the possibility of both higher OS (80% chance of OS=28 months) as well as lower OS (20% chance of OS=22 months). A multiple random staircase design was used to iteratively adjust OS probabilities in the “uncertain OS” option until the respondent was indifferent between the “certain OS” treatment option with 5.5-month PFS and the “uncertain OS” treatment option with 8-month PFS. The point of indifference was estimated by taking the midpoint between the maximum and minimum expected OS values for the "uncertain OS" treatment option, as observed in the final question of the multiple random staircase. The value of the increase in PFS was the difference between the expected OS of the “uncertain OS” option at the indifference point and the risk-neutral expected OS (26.8 months). Results: The 306 respondents had an average age of 52 years, 94% were insured, 76% were white, and 52% had a bachelor’s degree or higher. Among these respondents, 53% preferred the “uncertain OS” option with greater PFS over the “certain OS” option with lower PFS at baseline. However, preferences were highly heterogeneous; 19.6% preferred the “uncertain OS” treatment even when the probability of lower OS (22 months) was 90% whereas 24.8% did not choose to take any risk and always preferred the “certain OS” option, even if the probability of greater OS (28 months) was 95%. On average, respondents valued the “uncertain OS” treatment profile more as they were willing to forego 0.96 months of certain OS in exchange for a 2.5-month increase in PFS and the possibility for extended survival. Conclusion: On average, women attributed more value to increases in PFS even if this meant there was some possibility of a lower OS. However, preferences varied significantly across individuals in the sample. Because, on average, patients are willing to trade off OS for increases in PFS, shared decision-making processes should be considered to ensure mBC patient care aligns with individual preferences. Citation Format: J. Kim, K. Spurrier, M. Jakobsson, B. Hauber, J. Doan, B. Korytowsky, J. Shafrin. Quantifying the value of progression-free survival in breast cancer treatment among a general population of US women [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 PS5-12-02.