Geographic Access, Transportation Resources, and Early-Stage Lung Cancer Treatment Among Socioeconomically Disadvantaged Patients

BACKGROUND: A recent study reported that geographic access to cancer care was associated with guideline-recommended treatment for early-stage non-small cell lung cancer (NSCLC), particularly among uninsured and Medicaid patients. OBJECTIVE: To examine whether transportation resources modify the association between geographic access and treatment for early-stage NSCLC. METHODS: We used Surveillance, Epidemiology, and End Results data linked with Medicaid Analytic eXtracts Personal Summary files to identify patients aged 18 years or above with stage I/II NSCLC diagnosed during 2007-2019 who were uninsured or had Medicaid as primary/secondary payers at diagnosis. Geographic access to thoracic surgeons (TS) and radiation oncologists (RO) was calculated using the 2-step floating catchment area method and categorized into quartiles. Transportation resources were evaluated as county-level vehicle ownership and public transit availability, both dichotomized at the median level. Poisson regression with county-level clustering estimated rate ratios (RRs) for surgery and radiotherapy. RESULTS: Geographic access to TS was associated with surgery in both low (RR=0.92, 95% CI: 0.87-0.97 for lowest vs. highest access; P=0.66 for interaction) and high (RR=0.91, 95% CI 0.87-0.96) vehicle ownership counties. In contrast, geographic access to RO was associated with radiotherapy only among patients in counties with low vehicle ownership (RR=0.81, 95% CI: 0.74-0.89; P=0.01 for interaction), but not those in counties with high vehicle ownership (RR=0.96, 95% CI: 0.88-1.04). Similar patterns were observed in metropolitan counties with low vehicle ownership and limited public transit availability. CONCLUSIONS: Local transportation resources modified the association between geographic access and radiotherapy, but not surgery. Improving transportation access may enhance radiotherapy use for NSCLC.