Abstract PS5-11-19: Insurance Type Predicts Time-to-Approval for Proton Therapy in Breast Cancer

Abstract Background: Proton therapy (PT) is an advanced form of radiation therapy that offers dosimetric advantages over conventional photon therapy, particularly in sparing cardiac and pulmonary structures in patients with breast cancer. While PT may reduce long-term toxicity and improve quality of life, access remains limited due to cost, availability, and especially insurance-related hurdles. Prior authorization requirements, peer-to-peer reviews, and lengthy appeals can delay care, with disparities in access often correlating with insurance type. This study investigates whether insurance structure influences time-to-approval and denial rates for breast cancer patients receiving PT. Methods: A retrospective analysis was conducted on 111 breast cancer patients treated with PT at a National Cancer Institute-designated Comprehensive Cancer Center between August 2020 and November 2023. Patients were categorized by insurance type: public (Medicare/Medicaid), private (commercial PPO/HMO), and marketplace (Affordable Care Act plans). The primary endpoint was time from initial insurance submission to formal approval. Secondary endpoints included denial rates and success at each appeal stage. Statistical comparisons were performed using Mann-Whitney U tests for approval times and Fisher’s exact tests for denial rates, with significance defined as p < 0.05. Results: Significant disparities in time-to-approval were observed across insurance groups. Public insurance had the shortest mean approval time (16.6 days), followed by private (34.0 days), and marketplace plans (55.6 days). Median approval times mirrored this trend at 8, 27, and 47 days, respectively. All pairwise comparisons were statistically significant (p < 0.01). Marketplace insurance was associated with the greatest variability and highest rate of initial denial (59%), compared to 27% for private and 14% for public plans. Among denied marketplace patients, approval was eventually obtained in 100% of cases, but typically only after undergoing multiple appeal stages, including external review. First-level and peer-to-peer appeal success rates for this group were low at 33% and 31%, respectively, contributing to prolonged authorization timelines. Conclusions: Insurance structure significantly impacts access to PT for breast cancer patients. Marketplace insurance is associated with longer approval times and higher denial rates despite equivalent clinical indications. Public insurance demonstrated the most efficient and consistent approval process. These findings highlight insurance type as a structural determinant of care, independent of medical necessity, and underscore the need for payer reform to ensure equitable access to advanced radiation technologies. Streamlined authorization protocols, insurer-provider collaboration, and standardized clinical criteria may reduce delays and improve equity in cancer treatment delivery. Citation Format: A. S. Saini, M. T. Gompels, N. F. Khosrowzadeh, K. R. Chambers, K. Samimi, A. P. Dhawan, C. G. Washington, J. J. Meshman, . Insurance Type Predicts Time-to-Approval for Proton Therapy in Breast Cancer [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 PS5-11-19.