Structural Vulnerability in the United States Radiation Oncology Delivery System: Predictors and Consequences of Practice Site Disappearance.

Abstract

We sought to identify predictors of radiation oncology (RO) practice-site disappearance in the United States between 2018-2025, characterize how turnover reshapes county-level treatment capacity, and understand how counties with versus without RO access in 2025 differed in terms of sociodemographic and health system features. We examined the Centers for Medicare & Medicaid Services National Downloadable File to define an RO practice site as a unique physical location, identified using standardized address validation. Multivariable discrete-time logistic regression estimated the odds of site disappearance from year t to t+2 by hospital affiliation status, rurality, and organizational size. County-level analyses classified net change in local RO site counts through 2025, mapped regional patterns, and quantified remaining capacity. Separately, we compared sociodemographic and health system characteristics between counties with versus without an RO site in 2025. National RO site counts appeared stable but masked substantial turnover. In multivariable analysis, freestanding sites had higher odds of disappearance than hospital-affiliated sites (OR 1.56; 95% CI 1.24-1.95; P < 0.01), and sites located in rural counties had higher odds than those in urban counties (OR 1.44; 95% CI 1.23-1.69; P < 0.01). County-level net loss of sites occurred in 13.6% (427/3,144) of counties. Among loss counties, urban areas retained an average of 3.66 sites by 2025, versus 0.43 and 0.28 in rural-adjacent and rural-nonadjacent counties, respectively. 68.5% (2,154/3,144) of counties, home to 50.8 million people, lacked an RO practice site in 2025. These no-access counties had, on average, higher poverty and uninsurance rates, lower incomes, and fewer primary care physicians than counties with RO access. Freestanding sites and rural sites have experienced higher odds of disappearance in recent years. The large, socioeconomically vulnerable population currently residing in counties without RO access underscores the need for policies that strengthen practice resilience in structurally high-risk communities.