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Science Spotlight

Access to Prostate Cancer Clinical Trials: A County-Level Analysis

From the Bansal Group, Public Health Sciences Division

Although it’s critical to include minority populations in cancer clinical trials to aid in the generalizability of the outcomes, these populations are less likely to participate in clinical trials. To make matters worse, one study reported that minority populations’ enrollment rate was lower in 2003-2016 compared to 1996-2002.  The Bansal Group, from the Public Health Sciences Division, focused on the underrepresentation of African Americans in prostate cancer trials.  African American men’s prostate cancer incidence rate is 70% higher and their mortality rate is 2.5 times higher compared to White men.  Previous literature has determined disparities in access to prostate cancer clinical trials; barriers to participation include lack of knowledge, fear, and mistrust of clinical trials and even the medical establishment. However, no study has evaluated whether scarcity of cancer facilities that conduct prostate cancer within counties where they reside contributes an additional barrier to participation in clinical trials.  The Bansal Group investigated the relationship between the proportion of African Americans in the 3,145 counties in the U.S. and access to local cancer facilities. They also investigated the relationship between the percentage of African Americans in each county and number of available prostate cancer treatment trials per capita per year from 2008 to 2015. The study is published in JNCI Cancer Spectrum.

First, the Bansal group created a database of county-level data linkage of all US counties.  They utilized the 2016 Aggregate Analysis of ClinicalTrials.gov database to collect data on phase II and III prostate cancer clinical trials that were recruiting participants from 2008 until 2015.  Second, they controlled for geographic and socioeconomic factors and aggregated open cancer clinical trial sites by county.  Demographic, county-level socioeconomic, and health-care facility data were from the 2014-2015 Area Health Resource File. The location of all cancer care facilities was obtained from the National Cancer Institute Comprehensive Cancer Centers and the NCI Community Oncology Research Program. Multivariable logistic regression was utilized to assess the relationship between the proportion of African Americans in a county with available, local cancer facilities. A negative binomial regression model was utilized to evaluate the association of the proportion of African Americans in a county with the rate of available prostate cancer clinical trials per year.

According to the results, counties with higher proportions of African Americans seem less likely to have access to cancer facilities.  After adjusting for potential confounders, a 10-percentage point increase in the proportion of African Americans (e.g., comparing counties with 10% African Americans versus 20% African Americans) was associated with a 15% decrease in the odds of cancer center in the county. Furthermore, among counties with cancer facilities, those with higher proportions of African Americans appear to have fewer prostate cancer trials available per capita per year. After adjusting for potential confounders, a 10-percentage point increase in the proportion of African Americans was associated with a 10% lower rate of prostate cancer trials per year.

In this study, the Bansal group found that African Americans seem less likely to have access to cancer treatment trials within their counties.  However, they note, importantly, that the high association between race and socioeconomic status means that the effect of each cannot be fully disentangled, especially using population-level data.

The Bansal Group elaborates on the strengths of the study, “We created a novel, extensive data linkage and studied 2 specific access barriers – availability of cancer facilities than can run clinical trials and availability of prostate cancer clinical trials at those facilities.  Our study adds to current knowledge of the factors that may contribute to underrepresentation of African Americans in prostate cancer clinical trials by showing that patients are unable to enroll in trials simply because few trials are available to them. Our findings are critical for ensuring generalizability of clinical trial results and the subsequent adoption of clinical trial evidence to inform decision-making and policy.” The Bansal Group elaborated on future implications, “Future clinical trials in prostate cancer therapy should account for these barriers and include targeted strategies to ensure adequate availability of enrollment sites in regions with high concentrations of African Americans. Also, future studies should investigate whether similar disparities hold in other cancers among African Americans. “

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This research was supported by the National Cancer Institute of the National Institutes of Health.

Fred Hutch/UW Cancer Consortium member Aasthaa Bansal led this work.

Wang WJ, Ramsey SD, Bennette CS, Bansal A. Racial disparities in access to prostate cancer clinical trials: a county-level analysis. JNCI Cancer Spectrum. 2022 Feb;6(1):pkab093.