Radiotherapy capabilities, population, average income, and health insurance status as predictors of cancer mortality at the county level in the united states

Sufficient radiotherapy capacity at the country level is commonly seen in high income countries and is an essential factor in access to high quality cancer care. However, universal access is not always possible due to other factors beyond the commonly used parameter of machines per million population. This study aims to assess the barriers cancer patients in a high-income country face in accessing radiotherapy, and how this impacts cancer mortality.This cross-sectional study utilized United States county level oncologic and demographic data obtained from Centers for Disease Control and Prevention and the International Atomic Energy Agency Directory of Radiotherapy Centers. Radiotherapy facilities in the United States were mapped using Geographic Information Systems software. Univariate analysis was used to identify whether distance to a radiotherapy center or various socioeconomic factors were predictive of all-cancer mortality-to-incidence ratios. Variables that were deemed to be significant (p ≤ 0.05) on univariate analysis were then included in a step-wise backwards elimination method of multiple regression analysis.Among the United States counties studied, 31.3% of counties have at least one radiotherapy facility and 8.3% have five or more radiotherapy facilities. Median linear distance from a county's centroid to the nearest radiotherapy center was 36 Km and the median county all-cancer mortality to incidence ratio (MIR) was 0.37. The ratio of radiotherapy centers, linear accelerators and brachy therapy units per 1 million people were significantly associated with all-cancer MIR (p<0.05). Greater distance to radiotherapy facilities, lower county population, lower average income per county, and higher proportion of patients without health insurance were statistically significant predictors of increased all-cancer MIR (R-squared: 0.2113, F = 94.22, p<0.001).This analysis used unique high-quality datasets to identify significant barriers to radiotherapy access that correspond to higher cancer mortality at the county level. Geographic access, personal income, and insurance status all contribute to these concerning disparities. Efforts and novel strategies to address and minimize these barriers are needed to ensure access to care and improve oncologic outcomes.