OBJECTIVES: To investigate the annual trend and geographic pattern of cancer clinical trials and associated factors.

METHODS: This cross-sectional study used county-level information from ClinicalTrials.gov (AACT) database and several public data sources for county-level characteristics in the US and the US territories. Analyses were conducted from 2010 to 2022.

The main outcome was the number and rate of new cancer clinical trials from 2010 to 2021. We analyzed the overall pattern of cancer clinical trial over 12 years and the geographical distribution of trial sites across the US. Coefficients were calculated for cancer clinical trial rate per capita adjusting for county-level characteristics.

RESULTS: There were 12,416 cancer clinical trials from 2010 to 2021 and they took place in 223,576 different sites in the United States. From 2013 to 2018, the number of cancer clinical trials significantly increased by 6.0% per year (p=.04) then this increasing trend halted after 2018. Among 3220 counties in the US and US territories, only 937 (29%) counties had cancer clinical trial sites. We found that higher income level and rate medical specialists, and lower proportion of minority population were associated with higher trial rates. Counties with larger minorities population were associated with lower odds of having at least one cancer clinical trial. Higher rates of medical specialist, larger population, and higher age, income, and education level were associated with higher likelihood of having at least one cancer clinical trial.

CONCLUSIONS: There were significant county-level disparities in cancer trial rates per capita associated with sociodemographic factors even when adjusting for cancer incidence rate. Our findings suggest increasing healthcare access and improving education and economic status would potentially promote the development of cancer clinical trials. Meanwhile, healthcare providers and facilities should also consider include more minority population into cancer trials.