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SAN ANTONIO -- A lack of access to prostate cancer clinical trials in socially vulnerable areas of the U.S. was associated with significantly higher prostate cancer mortality rates, according to a cross-sectional analysis.

Of the 3,142 U.S. counties included in the analysis, 41.7% had any prostate cancer trial, with the most socially vulnerable counties having a lower proportion of trials compared with the least vulnerable counties (27.6% vs 46.9%, P<0.05), reported Rishi Sekar, MD, of the University of Michigan in Ann Arbor, during a presentation at the American Urological Association annual meeting.

Of note, the most vulnerable counties had a lower prostate cancer incidence rate (mean 393.8 vs 411.7 per 100,000 people, P<0.05), but a higher prostate cancer mortality rate (mean 85.7 vs 72.0 per 100,000 people, P<0.05).

On the other hand, the presence of a trial was associated with lower mortality. On adjusted analysis, the most vulnerable counties were associated with decreased odds of having any trial (OR 0.3, 95% CI 0.2-0.4) and increased prostate cancer mortality (adjusted difference 10.8, 95% CI 7.4-14.3), while the presence of any trial was associated with decreased prostate cancer mortality (adjusted difference -6.9, 95% CI -9.1 to -4.7).

"It's a trend we really don't want to see," Sekar said. "We would hope our trials are available for patients who may benefit the most -- patients with advanced disease, metastatic disease, where mortality rates are presumably higher -- but we see this big mismatch where these trial opportunities are."

Underrepresentation in clinical trials "is a huge problem," he added, noting that just 5% to 7% of eligible patients actually participate in trials even though surveys suggest that about 50% are willing to participate if provided the opportunity. Barriers to clinical trial participation include travel, cost, culture, and language.

Furthermore, social determinants of health (SDOH), such as income, education, neighborhood, and healthcare access, all play a role in determining health outcomes.

In the case of prostate cancer, he said, Black men have significantly higher prostate cancer incidence and mortality rates compared with white men, but are significantly underrepresented in prostate cancer trials.

In a discussion after the presentation, a member of the audience wanted to clarify the issue of causation, pointing out that most prostate cancer trials are phase I and II studies involving advanced cancer, and that in the majority of cases, these trials will not prevent prostate cancer mortality.

"I don't think a trial being present is going to reduce mortality in a direct, causal pathway," Sekar said, instead suggesting that the association between clinical trial availability and mortality is related to the way in which clinical trial and healthcare infrastructure is organized.

There are ongoing efforts by the National Cancer Institute (NCI) through its to accrue diverse patients and participants to NCI-approved research studies. "I hope this [study] works to support those efforts and programs like this," Sekar said.

"Opportunity matters," he added. "We can do everything we can to break down barriers to trial participation, like language barriers and cost issues, but the opportunity has to be accessible."

For this study, Sekar and colleagues looked at county-level prostate cancer clinical trial availability using ClinicalTrials.gov, prostate cancer incidence and mortality rates using Surveillance, Epidemiology, and End Results (SEER) Registry data, and population-level SDOH using the which comprises 16 U.S. census variables to determine the social vulnerability of every U.S. county based on social factors including poverty, lack of vehicle access, and crowded housing.

Counties were stratified into quintiles of SVI (least vulnerable to most vulnerable), and trial availability, prostate cancer incidence, and prostate cancer mortality were compared across SVI quintiles.

Phase II and III interventional prostate cancer clinical trials from 2007 to 2022 were included. The total number of clinical trials over the study period was calculated per county and population-adjusted for 100,000 residents.

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