Geographic disparity in the distribution of cancer clinical trials in the United States and the associated factors.

BACKGROUND: Little is known regarding the geographic disparity in the distribution of phase 1-3 clinical trials of new cancer treatments in the US and the associated factors.

OBJECTIVE: To examine county-level variation in the number of phase 1-3 cancer clinical trials and the associations between county characteristics and having phase 1-3 cancer clinical trials.

METHODS: We identified phase 1-3 cancer clinical trials started in the US between January 2008 and December 2022 from the Aggregate Analysis of ClinicalTrials.gov database. We analyzed the distribution of phase 1-3 cancer clinical trials at the county level. Using a mixed-effects regression with states as random intercepts, we estimated the associations between a county's median age, median household income, percentage of population from racial and ethnic minority groups, proportion of population aged 25 years or older with an educational attainment of bachelor's degree or higher, rurality, cancer incidence rate, and number of medical oncologists per population with having any phase 1-3 cancer clinical trial in a county.

RESULTS: After excluding trials that were suspended, terminated, and withdrawn, a total of 14,977 phase 1-3 cancer clinical trials started in the United States between January 2008 and December 2022 were included in the primary analysis. Only 1,333 out of 3,143 counties (42.4%) had 1 or more trial during this period. Counties that were rural, with lower median household income, a less educated population, fewer medical oncologists per population, and lower cancer incidence rates demonstrated a significantly lower likelihood of having phase 1-3 cancer clinical trials.

CONCLUSIONS: Our study revealed substantial geographic disparities in the distribution of phase 1-3 cancer clinical trials. Limited trial availability in low-income, low-education, low-oncologist, and rural areas can be a significant barrier to patient participation, potentially hindering adoption and worsening outcomes in disadvantaged populations.