43 Background: Availability of clinical trials for advanced cancers in the US varies greatly by geographical region, with just 81.5% of the population living within 30 miles of a PC clinical trial site (Swenson et al., JAMA Oncol. 2024). However, PC trial distribution in US, in relation to local geographic and socioeconomic barriers of access, has not yet been characterized. Methods: Utilizing the ClinicalTrials.gov trial database, we collated all interventional PC trials enrolling adults dated June 1, 2019, to June 1, 2025. We then compiled age-adjusted PC incidence and mortality rates for each US county with Social Vulnerability Index (SVI) derived from the CDC, NCI, and the Agency for Toxic Substances and Disease Registry data. To investigate PC trial availability, we utilized a zero-inflated negative binomial (ZINB) regression model. This model adjusts for the high proportion of counties without clinical trial sites and estimates potential influence of county characteristics on trial presence. Our results are conveyed in incidence rate ratios (IRRs). Trial characteristics were summarized using descriptive statistics. Model generation used the “pscl” package in R v4.4.3. Results: Our analysis yielded 884 eligible trials across 613 US counties (20.1%). 141 trials (16.0%) investigated curative therapeutics and treatments, while 571 trials (64.6%) investigated non-curative treatments and other methods of supportive care. 446 trials (50.5%) investigated metastatic PC. Just 20 trials (2.3%) explicitly investigated or included neuroendocrine PC. 464 trials (52.5%) were sponsored wholly or partially by pharmaceutical companies. Our model yielded no significant relationship between PC incidence or mortality rates and trial presence (IRR 1.00, 95% CI 0.999-1.01, p=0.16; IRR 1.01, 95% CI 0.98-1.03, p=0.65). Compared to counties with high SVI (highest social vulnerability), counties with low SVI had just over twice as many trials per household (IRR 2.05, 95% CI 1.54-2.74, p<0.001). Counties categorized as low-medium and medium-high also had significantly higher trial presence (IRR 1.63, 95% CI 1.22-2.19, p<0.001; IRR 1.61, 95% CI 1.21, 2.14, p<0.001). Conclusions: Trial availability remains a significant challenge in health care access. Our analysis indicated PC trials were significantly more concentrated in counties with low social vulnerability. Expanding trial access to more socially vulnerable counties is a significant and crucial step in promoting equitable access to vital care.
Mercier et al. (Sun,) studied this question.