Presenter(s)
N. Malik1, A. Khalil2, I. Yacoub3,4, K. Hsieh3,5, Q. Liu6, Z. Ma6, A. M. Chhabra3,5, I. J. Choi3,4, and C. B. Simone II3,4; 1Global Cancer Center, Johannesburg, South Africa, 2Allama Iqbal Medical College, Jinnah Hospital, Lahore, Pakistan, 3New York Proton Center, New York, NY, 4Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, 5Department of Radiation Oncology, Mount Sinai Health System, New York, NY, 6Department of Radiation Oncology, Mayo Clinic, Rochester, MN
Purpose/Objective(s): As proton beam therapy (PBT) becomes more accessible, understanding physician perspectives is important. We sought to characterize PBT referral patterns and evaluate factors influencing referrals, including practice setting, PBT access, geography, disease-site specialization, and perceived financial and insurance barriers. We hypothesize that PBT use is higher among physicians at academic centers and those with institutional access.
Materials/Methods: An 18-item, anonymous, IRB-approved online survey was emailed to 689 practicing U.S. radiation oncologists between 11/2025-01/2026. Responses were summarized with descriptive statistics. Group comparisons were made using chi-square, Fisher’s exact, Mann-Whitney U, or Kruskal-Wallis tests. Multiple linear regression identified independent predictors of referral proportion. Statistical significance was defined as p<0.05.
Results: There were 114 respondents (16.5% response rate) who practice in academic main (57.0%) or regional (28.9%) sites, private practice (15.8%), and/or community (11.4%) settings. Most respondents reported 5-10 (43.0%) or 11-20 (37.7%) years of independent practice. A majority (62.3%) had on-site or affiliated PBT access, and 42.1% treated with PBT. Over half (51.8%) of respondents referred =5% of their patients to PBT, whereas 13.2% referred >50%. Institutional access and insurance approval were cited as the most significant barriers to equitable PBT access; provider awareness was least significant. Among physicians who treat with PBT, cost had limited influence on referral decisions: 36.8% reported no influence, 28.1% moderate, and 9.6% strong. Among respondents treating with PBT, 45.8% reported that they refer predominantly based on perceived lower toxicity or better outcomes. In contrast, 29.7% of all respondents believed that center volume quotas drive the majority of PBT referrals. On univariable analysis, institutional PBT access (p=0.031) and practice setting (p=0.039) were associated with referrals, with disease-site specialization (p=0.068) trending toward significance, and years in practice and geography not associated. On multivariable analysis (R²=0.30), only institutional access (on-site ß=0.50, affiliated ß=0.41; p<0.001) remained independently predictive. Most physicians viewed PBT as an advanced but niche technology (47.8%), whereas 18.6% considered it top-of-the-range, and 1.8% considered it experimental. While 45.6% supported expanded PBT access, 76.4% reported that stronger evidence would increase referral confidence.
Conclusion: Our findings suggest that PBT referrals are driven primarily by institutional access rather than provider-level factors. Although most physicians view PBT as a credible modality, greater clinical evidence and reduced geospatial disparities in accessibility are needed to promote equitable and evidence-aligned use.