Trial growth and accessibility: Enrollment-weighted access to U.S. lung cancer clinical trials (2015–2025).

Abstract

e23116 Background: Although U.S. lung cancer trials have expanded over the past decade, trial counts alone may overestimate patient access when enrollment capacity is geographically concentrated. We developed an enrollment-weighted Trial Desert Index (eTDI) to measure patient-facing research opportunity and test whether growth in trial activity translated into equitable access. Methods: We identified U.S. interventional lung cancer trials registered on ClinicalTrials.gov and active from 2015 – 2025. Target enrollment was allocated across each trial’s active years and participating states using a systematic trial-to-state site mapping audit. eTDI was defined as enrollment slots per incident lung cancer case, reflecting patient-level opportunity. State-level five-year survival and early-stage diagnosis rates were examined to evaluate alignment with access. We quantified geographic concentration (Top-10 state share; Gini coefficient), identified high-burden/low-access states via incidence-eTDI percentile misalignment, and compared patterns by funder type. Results: By 2025, annualized U.S. lung trial enrollment capacity reached 74,093. Enrollment-weighted access was highly centralized, with the top 10 states accounting for 73.3% of enrollment capacity (Gini coefficient 0.693). The top five states were Florida (19.2%), Ohio (18.9%), California (6.7%), New York (6.4%), and Texas (4.4%). High-incidence states including Georgia, Illinois, Indiana, South Carolina, Wisconsin, and Louisiana demonstrated pronounced burden-access misalignment with persistently low enrollment-weighted access. Non-industry trials exhibited greater geographic concentration than industry-sponsored trials, with a top-10 state share of 82.5% versus 57.4%. Across states, lower eTDI frequently co-occurred with poorer publicly reported five-year survival or early-stage diagnosis rates. Conclusions: Despite substantial trial growth, enrollment-weighted access remains highly concentrated and poorly aligned with disease burden, limiting availability in high-incidence states. Metrics such as eTDI provide a reproducible framework for benchmarking access across trial networks, informing site decentralization, and enabling funder accountability to better align research capacity with population need. Enrollment-weighted lung trial access by selected states (2025). State Burden Enrollment Share (%) eTDI (Access) FL High 19.2 High OH High 18.9 High CA High 6.7 High NY High 6.4 High GA High 0.8 Low IL High 1.4 Low IN High 0.6 Low LA High 0.2 Low Selected high-incidence states illustrating heterogeneity in enrollment-weighted lung cancer trial access in 2025.