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

Racial disparity in prostate cancer: an outlook in genetic and molecular landscape

Prostate cancer (PCa) incidence, morbidity, and mortality rates are significantly impacted by racial disparities. Despite innovative therapeutic approaches and advancements in prevention, men of African American (AA) ancestry are at a higher risk of developing PCa and have a more aggressive and metastatic form of the disease at the time of initial PCa diagnosis than other races. Research on PCa has underlined the biological and molecular basis of racial disparity and emphasized the genetic aspect as the fundamental component of racial inequality. Furthermore, the lower enrollment rate, limited access to national-level cancer facilities, and deferred treatment of AA men and other minorities are hurdles in improving the outcomes of PCa patients. This review provides the most up-to-date information on various biological and molecular contributing factors, such as the single nucleotide polymorphisms (SNPs), mutational spectrum, altered chromosomal loci, differential gene expression, transcriptome analysis, epigenetic factors, tumor microenvironment (TME), and immune modulation of PCa racial disparities. This review also highlights future research avenues to explore the underlying biological factors contributing to PCa disparities, particularly in men of African ancestry.

Racial disparities in prostate cancer in the UK and the USA: similarities, differences and steps forwards

In the USA, Black men are approximately twice as likely to be diagnosed with and to die of prostate cancer than white men. In the UK, despite Black men having vastly different ancestral contexts and health-care systems from Black men in the USA, the lifetime risk of being diagnosed with prostate cancer is two-to-three times higher among Black British men than among white British men and Black British men are twice as likely to die of prostate cancer as white British men. Examination of racial disparities in prostate cancer in the USA and UK highlights systemic, socio-economic and sociocultural factors that might contribute to these differences. Variation by ancestry could affect incidence and tumour genomics. Disparities in incidence might also be affected by screening guidelines and access to and uptake of screening. Disparities in treatment access, continuity of care and outcomes could contribute to survival differences. In both localized and metastatic settings, equal access could diminish the observed disparities in both the USA and the UK. An understanding of behavioural medicine, especially an appreciation of cultural beliefs about illness and treatment, could inform and improve the ways in which health systems can engage with and deliver care to patients in minoritized groups affected by prostate cancer. Methods of promoting equity include targeting systemic barriers including systemic racism, proportional recruitment of patients into clinical trials, diversifying the health-care workforce and facilitating care informed by cultural humility. Actively engaging patients and communities in research and intervention might enable the translation of research into increasingly equitable care for patients with prostate cancer in the UK, the USA and globally.

Mediators of racial and ethnic inequities in clinical trial participation among patients with cancer, 2011-2023

BACKGROUND

Although racially and ethnically minoritized populations are less likely to participate in cancer trials, it is unknown whether social determinants of health (SDOH) explain these inequities. Here we identify SDOH factors that contribute to racial and ethnic inequities in clinical trial participation among patients with 22 common cancers.

METHODS

This retrospective cohort study used electronic health record data (2011-2023) linked to neighborhood (US Census tract) data from multiple sources. Patients were followed from diagnosis to clinical study drug receipt (proxy for trial participation), death, or last recorded activity. Associations were assessed using Cox proportional hazards models adjusted for clinical factors (year of diagnosis, age, sex, performance status, disease stage, cancer type). To elucidate which area-level SDOH underlie racial and ethnic inequities, mediation analysis was performed using nonlinear multiple additive regression tree models.

RESULTS

This study included 250 105 patients (64.7% non-Latinx White, 8.9% non-Latinx Black, 5.2% Latinx). Black and Latinx patients were more likely to live in economically or socially marginalized areas (eg, disproportionately minoritized [measure of segregation], limited English proficiency, low vehicle ownership) than White patients. Black (3.7%; hazard ratio = 0.55, 95% confidence interval [CI] = 0.52 to 0.60) and Latinx patients (4.4%; hazard ratio = 0.63, 95% CI = 0.58 to 0.69) were less likely to participate in trials than White patients (6.3%). Fewer patients in economically or socially marginalized neighborhoods participated in trials. Mediators explained 62.2% (95% CI = 49.5% to 74.8%) of participation inequities between Black and White patients; area-level SDOH-including segregation (29.9%, 95% CI = 21.2% to 38.6%) and vehicle ownership (11.6%, 95% CI = 7.0% to 16.1%)-were the most important mediators. Similarly, Latinx-White participation inequities were mediated (65.1%, 95% CI = 49.8% to 80.3%) by area-level SDOH, such as segregation (39.8%, 95% CI = 28.3% to 51.3%), limited English proficiency (11.6%, 95% CI = 2.8% to 20.4%), and vehicle ownership (9.6%, 95% CI = 5.8% to 13.5%).

CONCLUSIONS

To improve racial and ethnic diversity in cancer trials, efforts to address barriers related to adverse neighborhood SDOH factors are necessary.

Why location matters: associations between county-level characteristics and availability of National Cancer Oncology Research Program and National Cancer Institute sites

BACKGROUND

The majority of patients with cancer seek care at community oncology sites; however, most clinical trials are available at National Cancer Institute (NCI)-designated sites. Although the NCI National Cancer Oncology Research Program (NCORP) was designed to address this problem, little is known about the county-level characteristics of NCORP site locations.

METHODS

This cross-sectional analysis determined the association between availability of NCORP or NCI sites and county-level characteristic theme percentile scores from the Center for Disease Control and Prevention's Social Vulnerability Index themes. Health Resources and Services Administration's Area Health Resource Files were used to determine contiguous counties. We estimated risk ratios and 95% confidence intervals (CIs) using modified Poisson regression models to evaluate the association between county-level characteristics and site availability within singular and singular and contiguous counties.

RESULTS

Of 3141 included counties, 14% had an NCORP, 2% had an NCI, and 1% had both sites. Among singular counties, for a standard deviation increase in the racial and ethnic theme score, there was a 22% higher likelihood of NCORP site availability (95% CI = 1.10 to 1.36); for a standard deviation increase in the socioeconomic status theme score, there was a 24% lower likelihood of NCORP site availability (95% CI = 0.67 to 0.87). Associations were of smaller magnitude when including contiguous counties. NCI sites were located in more vulnerable counties.

CONCLUSIONS

NCORP sites were more often in racially diverse counties and less often in socioeconomically vulnerable counties. Research is needed to understand how clinical trial representation will increase if NCORP sites strategically increase their locations in more vulnerable counties.

PARP-ish: Gaps in Molecular Understanding and Clinical Trials Targeting PARP Exacerbate Racial Disparities in Prostate Cancer

PARP is a nuclear enzyme with a major function in the DNA damage response. PARP inhibitors (PARPi) have been developed for treating tumors harboring homologous recombination repair (HRR) defects that lead to a dependency on PARP. There are currently three PARPi approved for use in advanced prostate cancer (PCa), and several others are in clinical trials for this disease. Recent clinical trial results have reported differential efficacy based on the specific PARPi utilized as well as patient race. There is a racial disparity in PCa, where African American (AA) males are twice as likely to develop and die from the disease compared to European American (EA) males. Despite the disparity, there continues to be a lack of diversity in clinical trial cohorts for PCa. In this review, PARP nuclear functions, inhibition, and clinical relevance are explored through the lens of racial differences. This review will touch on the biological variations that have been explored thus far between AA and EA males with PCa to offer rationale for investigating PARPi response in the context of race at both the basic science and the clinical development levels.

Determining clinical perspectives and strategies for improving enrollment of minoritized communities in prostate cancer clinical trials

BACKGROUND

Black men and other minoritized populations have represented 4-5% or less of participants in most practice-informing clinical trials. This study sought to assess the knowledge, attitudes, and practices of clinicians around equity and inclusion in prostate cancer clinical trial initiatives in the United States.

METHODS

An anonymous, web-based questionnaire was administered via REDCap (Research Electronic Data Capture) with questions focused on inclusivity of minoritized populations with respect to race and ethnicity in prostate cancer clinical trials research. The survey link was distributed across the United States via several professional organizations, prostate cancer groups, and social media. Responses were analyzed both quantitatively (descriptive statistics) and qualitatively (thematic analysis).

RESULTS

Overall, 131 respondents completed the survey (70% self-identified as White, 17% as Asian, and 6% as Black). Most respondents practiced in an urban setting (89%). Of those who engaged in outreach with minoritized communities during the trial design process, 69% observed improved enrollment of minoritized populations. However, 18% of respondents noted that outreach alone does not overcome existing structural barriers to participation in clinical trials. Thematic analysis identified four key areas to address for improving equity: structural, health system, trial-/study-specific, and relationship-/engagement-related factors.

CONCLUSION

Study participants demonstrated a knowledge of the importance of improving equity in prostate cancer clinical trials research. Designing trials that reduce issues associated with access and improving community outreach were emphasized as key focus areas for reducing health disparities in prostate cancer clinical trials research.

The costs and inequities of precision medicine for patients with prostate cancer: A call to action

Financial toxicity is a growing problem in the delivery of cancer care and contributes to inequities in outcomes across the cancer care continuum. Racial/ethnic inequities in prostate cancer, the most common cancer diagnosed in men, are well described, and threaten to widen in the era of precision oncology given the numerous structural barriers to accessing novel diagnostic studies and treatments, particularly for Black men. Gaps in insurance coverage and cost sharing are 2 such structural barriers that can perpetuate inequities in screening, diagnostic workup, guideline-concordant treatment, symptom management, survivorship, and access to clinical trials. Mitigating these barriers will be key to achieving equity in prostate cancer care, and will require a multi-pronged approach from policymakers, health systems, and individual providers. This narrative review will describe the current state of financial toxicity in prostate cancer care and its role in perpetuating racial inequities in the era of precision oncology.

Disparities in time to prostate cancer treatment initiation before and after the Affordable Care Act

BACKGROUND

Delayed access to care may contribute to disparities in prostate cancer (PCa). The Affordable Care Act (ACA) aimed at increasing access and reducing healthcare disparities, but its impact on timely treatment initiation for PCa men is unknown.

METHODS

Men with intermediate- and high-risk PCa diagnosed 2010-2016 and treated with curative surgery or radiotherapy were identified in the National Cancer Database. Multivariable logistic regression modeled the effect of race and insurance type on treatment delay >180 days after diagnosis. Cochran-Armitage test measured annual trends in delays, and joinpoint regression assessed if 2014, the year the ACA became fully operationalized, was significant for inflection in crude rates of major delays.

RESULTS

Of 422,506 eligible men, 18,720 (4.4%) experienced >180-day delay in treatment initiation. Compared to White patients, Black (OR 1.79, 95% CI 1.72-1.87, p < 0.001) and Hispanic (OR 1.37, 95% CI 1.28-1.48, p < 0.001) patients had higher odds of delay. Compared to uninsured, those with Medicaid had no difference in odds of delay (OR 0.94, 95% CI 0.84-1.06, p = 0.31), while those with private insurance (OR 0.57, 95% CI 0.52-0.63, p < 0.001) or Medicare (OR 0.64, 95% CI 0.58-0.70, p < 0.001) had lower odds of delay. Mean time to treatment significantly increased from 2010 to 2016 across all racial/ethnic groups (trend p < 0.001); 2014 was associated with a significant inflection for increase in rates of major delays.

CONCLUSIONS

Non-White and Medicaid-insured men with localized PCa are at risk of treatment delays in the United States. Treatment delays have been consistently rising, particularly after implementation of the ACA.

Cross-Sectional Analysis of Clinical Trial Availability and North Carolina Neighborhood Social Vulnerability

PURPOSE

Residents of communities facing social vulnerability (eg, poverty) have limited access to clinical trials, leaving them susceptible to experiencing poor health outcomes. We examined the association between North Carolina county-level social vulnerability and available multiple myeloma (MM) trials.

METHODS

Using a novel data linkage between ClinicalTrials.gov, the 2019 American Community Survey, and the Centers for Disease Control and Prevention's Social Vulnerability Index, we investigated at the county level (1) availability of MM trial sites and (2) the relationship between Social Vulnerability Index and MM trial site availability using logistic regression.

RESULTS

Between 2002 and 2021, 229 trials were registered across 462 nonunique trial sites in 34 counties. Nearly 50% of trial sites were in academic medical centers, 80% (n = 372) of all trials were industry-sponsored, 60% (n = 274) were early-phase, and 50% (n = 232) were for patients with relapsed or refractory MM. Counties with low as opposed to high poverty rates had six times greater odds of having ≥ 1 MM trial sites (odds ratio [OR], 5.60; 95% CI, 1.85 to 19.64; P = .004). Counties with the lowest percentage of Black Indigenous Persons of Color and non-native English speakers had 77% lower odds (OR, 0.23; 95% CI, 0.07 to 0.69; P = .011) of having ≥ 1 trial sites. The effect remained significant after accounting for the presence of five academic medical centers (n = 95; OR, 0.18; 95% CI, 0.05 to 0.6; P = .008) and adjustment for metropolitan, suburban, or rural status (OR, 0.25; 95% CI, 0.07 to 0.81; P = .025).

CONCLUSION

Counties with the lowest poverty rates had more MM trial sites, whereas those with the lowest percentage of Black Indigenous Persons of Color populations had fewer MM trial sites. Multilevel efforts are needed to improve the availability and access to trials for socially vulnerable populations.

An evaluation of race-based representation among men participating in clinical trials for prostate cancer and erectile dysfunction

Background

Inclusion of ethnic/racial minorities in clinical trials is essential to fully assess therapeutic efficacy. It is well-known that populations respond dissimilarly to interventions. Our objective is to analyze the inclusion of minority men in clinical trials for erectile dysfunction (ED).

Methods

We searched ClinicalTrials.gov for the disease keyword: "Erectile Dysfunction" and used "Prostate Cancer" for comparison. Completed trials which reported demographic data were included for analysis. Literature was reviewed to determine the prevalence of ED and prostate cancer (PC) among Hispanic, Black, White, and Asian men. The proportion of individuals of each group that participated in trials is divided by the proportion of each group in the disease population to calculate the "Participation to Prevalence Ratio" (PPR). PPRs between 0.8 and 1.2 indicates adequate representation, <0.8 is under-representation and >1.2 is over-representation.

Results

A total of 312 trials were assessed: 289 for prostate cancer and 23 for ED. Hispanic men comprised 11.8% of ED trial participants and 4.6% of prostate cancer trial participants, yet represented 18% of ED patients and 7.3% of PC patients. Black/African-American (AA) men accounted for 10.2% of ED trial participants and 9.4% of PC trial participants, but comprise 16% of ED patients, and 16.3% of PC patients. Hispanic and AA men are under-represented in trials for ED and Prostate Cancer (Hispanic ED PPR = 0.66; Hispanic PC PPR = 0.63; AA ED PPR = 0.64; AA PC PPR = 0.58).

Conclusion

Our analysis shows that both Hispanic and AA men are underrepresented in both ED and PC clinical trials.