Main Session
Sep
29
PQA 06 - Genitourinary Cancer, Gynecological Cancer, and Health Care Access and Engagement
3715 - The Influence of Payer Type vs. Community Characteristics in Shaping Realized Access to Proton Therapy
Presenter(s)
Peter Orio, DO, MS, FASTRO - Dana-Farber Cancer Institute , Boston, MA
P. F. Orio III1, R. S. Punglia2, T. Frandsen3, and P. M. Devlin1; 1Department of Radiation Oncology, Brigham and Women’s Hospital and Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, 2Department of Radiation Oncology, Dana-Farber Cancer Institute and Brigham and Women’s Hospital, Boston, MA, 3GT Medical Technologies, Tempe, AZ
Purpose/Objective(s):
Studies examining access to proton beam therapy (PBT) have relied on frameworks that implicitly assume geographic availability translates to realized utilization. However, the degree to which community-level factors influence realized access once a center is established is not well understood. We evaluated whether realized access varies by payer type and whether community characteristics account for this variation.Materials/Methods:
We conducted a cross-sectional analysis of 51,883 patients at 38 proton centers (2021-2024) using an all-payer claims database linked to census-derived market characteristics, CDC’s Social Vulnerability Index (SVI), and CMS enrollment data. Centers were assigned a 100-mile catchment (50/150-mile sensitivity analyses were similar). Payer benchmarks were obtained from the American Community Survey (ACS). CMS penetration rates stratified Medicare into traditional Medicare (TM) and Medicare Advantage (MA). Analyses were limited to patients whose vendor-defined origination ZIP code fell within the catchment to mitigate bias from regional/national referrals. The primary endpoint was Representation Index (RI), the ratio of realized to expected payer share (RI<1 = underrepresentation). Medicaid RI was calculated but excluded from inferential analyses due to claims data limitations. Payer-specific RIs were tested against expected values and compared between payer types using Wilcoxon tests; associations between community-level predictors and RIs were assessed with Spearman correlations.Results:
Commercial was underrepresented (median RI=0.32; P<0.001) and Medicaid descriptively low. Medicare was overrepresented (TM median RI=5.42; P<0.001; MA median RI=1.69), with MA substantially lower than TM within the same centers (paired Wilcoxon p<0.001). Because ACS benchmarks reflect all ages and cancer incidence rises with age, Medicare overrepresentation is expected; TM vs MA is presented as a within-Medicare comparison. No community-level predictor was statistically significant for any payer-specific RI (SVI, poverty, local MA penetration; all P>0.33).Conclusion:
When geographic availability is held constant, realized access to PBT aligns more closely with payer than surrounding community vulnerability or local payer composition. These findings suggest payer-related factors may be more closely associated with PBT utilization than proximity or vulnerability-based access frameworks. Policies aimed at improving equity in advanced radiotherapy may need to address payer-level administrative and reimbursement factors.