Individual Patient Data Analysis of Randomized Clinical Trials: Impact of Black Race on Castration-resistant Prostate Cancer Outcomes

Race has no impact on prostate cancer-specific mortality, when comparing patients with similar risk of other-cause mortality: An analysis of a population-based cohort

BACKGROUND

Other-cause mortality (OCM) can serve as a surrogate for access-to-care. The authors sought to compare prostate cancer-specific mortality (PCSM) in Black versus White men matched based on their calculated OCM risk.

METHODS

The Surveillance, Epidemiology, and End Results (SEER) database was queried for Black and White men diagnosed with prostate cancer between 2004 to 2009, to collect long-term follow-up. A Cox regression was used to calculate the OCM risk using all available covariates. This calculated OCM risk was used to construct a 1:1 propensity score matched (PSM) cohort. Then, a competing-risks multivariable tested the impact of race on PCSM.

RESULTS

A total of 94,363 patients were identified, with 19,398 Black men and 74,965 White men. The median (IQR) follow-up was 11.3 years (9.8-12.8). In the unmatched-cohort at 10-years, PCSM and OCM were 5.5% versus 3.5% and 13.8% versus 8.4% in non-Hispanic Black (NHB) versus non-Hispanic White (NHW) patients (all p < .0001). The standardized mean difference was <0.15 for all covariates, indicating a good match. In the matched cohort at 10-years, OCM was 13.6% and 10.0% in NHB versus NHW (p < .0001), whereas the PCSM was 5.3% versus 4.7% (p < .01). On competing-risks multivariable analysis on PCSM, Black men had a hazard ratio of 1.08 (95% confidence interval, 0.98-1.20) compared to White men with a p = .13.

CONCLUSIONS

The results of this study showed similar PCSM in Black and White patients, when matched with their calculated OCM risk. This report is the first to indicate at a population-based level that race has no impact on PCSM.

PLAIN LANGUAGE SUMMARY

Prostate cancer is a very common cancer among men and it is associated with health disparities that disproportionately impact Black men compared to White men. There is an on-going discussion of whether disparities between these two groups stem from genetic or environmental factors. This study sought to examine if matching based on overall health status, a proxy for the impact of social determinants of health, mitigated significant differences in outcomes. When matched using risk of death from any cause other than prostate cancer, Black and White men had no significant differences in prostate cancer death.

Estimating the impact of enhanced care at minority-serving hospitals on disparities in the treatment of breast, prostate, lung, and colon cancers

BACKGROUND

The objective of this study was to quantify disparities in cancer treatment delivery between minority-serving hospitals (MSHs) and non-MSHs for breast, prostate, nonsmall cell lung, and colon cancers from 2010 to 2019 and to estimate the impact of improving care at MSHs on national disparities.

METHODS

Data from the National Cancer Database (2010-2019) identified patients who were eligible for definitive treatments for the specified cancers. Hospitals in the top decile by minority patient proportion were classified as MSHs. Multivariable logistic regression adjusted for patient and hospital characteristics compared the odds of receiving definitive treatment at MSHs versus non-MSHs. A simulation was used to estimate the increase in patients receiving definitive treatment if MSH care matched the levels of non-MSH care.

RESULTS

Of 2,927,191 patients from 1330 hospitals, 9.3% were treated at MSHs. MSHs had significant lower odds of delivering definitive therapy across all cancer types (adjusted odds ratio: breast cancer, 0.83; prostate cancer, 0.69; nonsmall cell lung cancer, 0.73; colon cancer, 0.81). No site of care-race interaction was significant for any of the cancers (p > .05). Equalizing treatment rates at MSHs could result in 5719 additional patients receiving definitive treatment over 10 years.

CONCLUSIONS

The current findings underscore systemic disparities in definitive cancer treatment delivery between MSHs and non-MSHs for breast, prostate, nonsmall cell lung, and colon cancers. Although targeted improvements at MSHs represent a critical step toward equity, this study highlights the need for integrated, system-wide efforts to address the multifaceted nature of racial and ethnic health disparities. Enhancing care at MSHs could serve as a pivotal strategy in a broader initiative to achieve health care equity for all.

A qualitative approach to understanding the drivers of unequal receipt of definitive therapy for Black men with prostate cancer in Massachusetts

BACKGROUND

Despite mandated insurance coverage since 2006 and robust health infrastructure in urban settings with high concentrations of minority patients, race-based disparities in prostate cancer (PCa) treatment persist in Massachusetts. In this qualitative study, the authors sought to identify factors driving inequities in PCa treatment in Massachusetts.

METHODS

Four hospitals offering PCa treatment in Massachusetts were selected using a case-mix approach. Purposive sampling was used to conduct semistructured interviews with hospital stakeholders. Additional interviews were conducted with representatives from grassroots organizations providing PCa education. Two study staff coded the interviews to identify major themes and recurrent patterns.

RESULTS

Of the 35 informants invited, 25 participated in the study. Although national disparities in PCa outcomes were readily discussed, one half of the informants were unaware that PCa disparities existed in Massachusetts. Informants and grassroots organization representatives acknowledged that patients with PCa are willing to face transportation barriers to receive treatment from trusted and accommodating institutions. Except for chief equity officers, most health care providers lacked knowledge on accessing or using metrics regarding racial disparities in cancer outcomes. Although community outreach was recognized as a potential strategy to reduce treatment disparities and engender trust, informants were often unable to provide a clear implementation plan.

CONCLUSIONS

This statewide qualitative study builds on existing quantitative data on the nature and extent of disparities. It highlights knowledge gaps in recognizing and addressing racial disparities in PCa treatment in Massachusetts. Improved provider awareness, the use of disparity metrics, and strategic community engagement may ensure equitable access to PCa treatment.

PLAIN LANGUAGE SUMMARY

Despite mandated insurance and urban health care access, racial disparities in prostate cancer treatment persist in Massachusetts. This qualitative study revealed that, although national disparities were acknowledged, awareness about local disparities are lacking. Stakeholders highlighted the importance of ancillary services, including translators, rideshares, and navigators, in the delivery of care. In addition, whereas hospital stakeholders were aware of collected equity outcomes, they were unsure whether and who is monitoring equity metrics. Furthermore, stakeholders agreed that community outreach showed promise in ensuring equitable access to prostate cancer treatment. Nevertheless, most interviewed stakeholders lacked clear implementation plans.

Disparities With Systemic Therapies for Black Men Having Advanced Prostate Cancer: Where Do We Stand?

PURPOSE

Prostate cancer represents the most common cancer diagnosis in Black men and is the second leading cause of cancer death in this population. Multilevel disparities have been well-documented in Black men with prostate cancer and play a role in poorer survival outcomes when compared with White men with prostate cancer. In this review, we highlight the changing trend in disparities for systemic therapy outcomes in Black men diagnosed with metastatic prostate cancer.

METHODS

We reviewed data from real-world registries and prospective clinical trials with a particular focus on equal access settings to compare outcomes to systemic therapies between Black and White men with metastatic prostate cancer.

RESULTS

In metastatic prostate cancer, there is growing evidence to suggest that Black men may have similar, if not better, outcomes to systemic therapies than White men with advanced disease, as corroborated by prospective studies and clinical trials where health care delivery and follow-up are more likely to be standardized.

CONCLUSION

This review illustrates the importance of nonbiological drivers of racial disparities in Black men with advanced prostate cancer. Mitigating barriers to health care access and delivery as well as including participation in clinical trials will be pivotal to ongoing efforts to address disparities in systemic therapy outcomes for Black men with metastatic prostate cancer.

Prostate Cancer, Race, and Health Disparity: What We Know

ABSTRACT

Prostate cancer (PCa) in African American men is one of the most common cancers with a great disparity in outcomes. The higher incidence and tendency to present with more advanced disease have prompted investigators to postulate that this is a problem of innate biology. However, unequal access to health care and poorer quality of care raise questions about the relative importance of genetics versus social/health injustice. Although race is inconsistent with global human genetic diversity, we need to understand the sociocultural reality that race and racism impact biology. Genetic studies reveal enrichment of PCa risk alleles in populations of West African descent and population-level differences in tumor immunology. Structural racism may explain some of the differences previously reported in PCa clinical outcomes; fortunately, there is high-level evidence that when care is comparable, outcomes are comparable.

Biomarker-Directed Therapy in Black and White Men With Metastatic Castration-Resistant Prostate Cancer

Importance

Black men have higher incidence and mortality from prostate cancer. Whether precision oncology disparities affect Black men with metastatic castration-resistant prostate cancer (mCRPC) is unknown.

Objective

To compare precision medicine data and outcomes between Black and White men with mCRPC.

Design, Setting, and Participants

This retrospective cohort study used data collected by the Prostate Cancer Precision Medicine Multi-Institutional Collaborative Effort (PROMISE) consortium, a multi-institutional registry with linked clinicogenomic data, from April 2020 to December 2021. Participants included Black and White patients with mCRPC with molecular data. Data were analyzed from December 2021 to May 2023.

Exposures

Database-reported race and ethnicity.

Main Outcomes and Measures

The primary outcome was the frequency of actionable molecular data, defined as the presence of mismatch repair deficiency (MMRD) or high microsatellite instability (MSI-H), homologous recombination repair deficiency, or tumor mutational burden of 10 mutations per megabase or greater. Secondary outcomes included the frequency of other alterations, the type and timing of genomic testing performed, and use of targeted therapy. Efficacy outcomes were prostate-specific antigen response rate, site-reported radiographic response, and overall survival.

Results

A total of 962 eligible patients with mCRPC were identified, including 204 Black patients (21.2%; median [IQR] age at diagnosis, 61 [55-67] years; 131 patients [64.2%] with Gleason scores 8-10; 92 patients [45.1%] with de novo metastatic disease) and 758 White patients (78.8%; median [IQR] age, 63 [57-69] years; 445 patients [58.7%] with Gleason scores 8-10; 310 patients [40.9%] with de novo metastatic disease). Median (IQR) follow-up from mCRPC was 26.6 (14.2-44.7) months. Blood-based molecular testing was more common in Black men (111 men [48.7%]) than White men (317 men [36.4%]; P < .001). Rates of actionable alterations were similar between groups (65 Black men [32.8%]; 215 White men [29.1%]; P = .35), but MMRD or MSI-H was more common in Black men (18 men [9.1]) than White men (36 men [4.9%]; P = .04). PTEN alterations were less frequent in Black men than White men (31 men [15.7%] vs 194 men [26.3%]; P = .003), as were TMPRSS alterations (14 men [7.1%] vs 155 men [21.0%]; P < .001). No other differences were seen in the 15 most frequently altered genes, including TP53, AR, CDK12, RB1, and PIK3CA. Matched targeted therapy was given less frequently in Black men than White men (22 men [33.5%] vs 115 men [53.5%]; P = .008). There were no differences in response to targeted therapy or survival between the two cohorts.

Conclusions and Relevance

This cohort study of men with mCRPC found higher frequency of MMRD or MSI-H and lower frequency of PTEN and TMPRSS alterations in Black men compared with White men. Although Black men received targeted therapy less frequently than White men, no differences were observed in clinical outcomes.

Racial/ethnic disparities in the cause of death among patients with prostate cancer in the United States from 1995 to 2019: a population-based retrospective cohort study

Background

Racial/ethnic disparities in prostate cancer are reported in the United States (US). However, long-term trends and contributors of racial/ethnic disparities in all-cause and cause-specific death among patients with prostate cancer remain unclear. We analysed the trends and contributors of racial/ethnic disparities in prostate cancer survivors according to the cause of death in the US over 25 years.

Methods

In this retrospective, population-based longitudinal cohort study, we identified patients diagnosed with first primary prostate cancer between 1995 and 2019, with follow-up until Dec 31, 2019, using population-based cancer registries' data from the Surveillance, Epidemiology, and End Results (SEER) Program. We calculated the cumulative incidence of death for each racial/ethnic group (Black, white, Hispanic, Asian or Pacific Islander [API], and American Indian or Alaska Native [AI/AN] people), by diagnostic period and cause of death. We quantified absolute disparities using rate changes for the 5-year cumulative incidence of death between racial/ethnic groups and diagnostic periods. We estimated relative (Hazard ratios [HR]) racial/ethnic disparities and the percentage of potential factors contributed to racial/ethnic disparities using Cox regression models.

Findings

Despite a decreasing trend in the cumulative risk of death across five racial/ethnic groups, AI/AN and Black patients consistently had the highest rate of death between 1995 and 2019 with an adjusted HR of 1.48 (1.40-1.58) and 1.40 (1.38-1.42) respectively. The disparities in all-cause mortality between AI/AN and white patients increased over time, with adjusted HR 1.32 (1.17-1.49) in 1995-1999 and 1.95 (1.53-2.49) in 2015-2019. Adjustment of stage at diagnosis, initial treatment, tumor grade, and household income explained 33% and 24% of the AI/AN-white and Black-white disparities in all-cause death among patients with prostate cancer.

Interpretation

The enduring racial/ethnic disparities in patients with prostate cancer, call for new interventions to eliminate health disparities. Our study provides important evidence and ways to address racial/ethnic inequality.

Funding

National Key R&D Program of China, National Natural Science Foundation of China, Beijing Municipal Administration of Hospitals Clinical Medicine Development of Special Funding Support, the Open Research Fund from Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Key Projects of Philosophy and Social Sciences Research, Ministry of Education of China.

TCGA Expression Analyses of 10 Carcinoma Types Reveal Clinically Significant Racial Differences

Epidemiological studies reveal disparities in cancer incidence and outcome rates between racial groups in the United States. In our study, we investigated molecular differences between racial groups in 10 carcinoma types. We used publicly available data from The Cancer Genome Atlas to identify patterns of differential gene expression in tumor samples obtained from 4112 White, Black/African American, and Asian patients. We identified race-dependent expression of numerous genes whose mRNA transcript levels were significantly correlated with patients' survival. Only a small subset of these genes was differentially expressed in multiple carcinomas, including genes involved in cell cycle progression such as CCNB1, CCNE1, CCNE2, and FOXM1. In contrast, most other genes, such as transcriptional factor ETS1 and apoptotic gene BAK1, were differentially expressed and clinically significant only in specific cancer types. Our analyses also revealed race-dependent, cancer-specific regulation of biological pathways. Importantly, homology-directed repair and ERBB4-mediated nuclear signaling were both upregulated in Black samples compared to White samples in four carcinoma types. This large-scale pan-cancer study refines our understanding of the cancer health disparity and can help inform the use of novel biomarkers in clinical settings and the future development of precision therapies.

Analysis of evolutionary dynamics and clonal architecture in prostate cancer

The extent to which clinical and genomic characteristics associate with prostate cancer clonal architecture, tumor evolution, and therapeutic response remains unclear. Here, we reconstructed the clonal architecture and evolutionary trajectories of 845 prostate cancer tumors with harmonized clinical and molecular data. We observed that tumors from patients who self-reported as Black had more linear and monoclonal architectures, despite these men having higher rates of biochemical recurrence. This finding contrasts with prior observations relating polyclonal architecture to adverse clinical outcomes. Additionally, we utilized a novel approach to mutational signature analysis that leverages clonal architecture to uncover additional cases of homologous recombination and mismatch repair deficiency in primary and metastatic tumors and link the origin of mutational signatures to specific subclones. Broadly, prostate cancer clonal architecture analysis reveals novel biological insights that may be immediately clinically actionable and provide multiple opportunities for subsequent investigation.

Statement of significance

Tumors from patients who self-reported as Black demonstrate linear and monoclonal evolutionary trajectories yet experience higher rates of biochemical recurrence. In addition, analysis of clonal and subclonal mutational signatures identifies additional tumors with potentially actionable alterations such as deficiencies in mismatch repair and homologous recombination.

Disparities in the Inclusion of Racial and Ethnic Minority Groups and Older Adults in Prostate Cancer Clinical Trials: A Meta-analysis

Importance

Prostate cancer (PCa) is marked by disparities in clinical outcomes by race, ethnicity, and age. Equitable enrollment in clinical trials is fundamental to promoting health equity.

Objective

To evaluate disparities in the inclusion of racial and ethnic minority groups and older adults across PCa clinical trials.

Data Sources

MEDLINE, Embase, and ClinicalTrials.gov were searched to identify primary trial reports from each database's inception through February 2021. Global incidence in age subgroups and US population-based incidence in racial and ethnic subgroups were acquired from the Global Burden of Disease and Surveillance, Epidemiology, and End Results 21 incidence databases respectively.

Study Selection

All phase 2/3 randomized PCa clinical trials were eligible for age disparity analyses. Trials recruiting exclusively from the US were eligible for primary racial and ethnic disparity analyses.

Data Extraction and Synthesis

This study was reported in accordance with Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guidelines. Data were pooled using a random-effects model.

Main Outcomes and Measures

Enrollment incidence ratios (EIRs), trial proportions (TPs) of participants 65 years or older or members of a racial and ethnic subgroup divided by global incidence in the corresponding age group, or US population-based incidence in the corresponding racial and ethnic subgroup, were calculated. Meta-regression was used to explore associations between trial characteristics and EIRs and trends in EIRs during the past 3 decades.

Results

Of 9552 participants among trials reporting race, 954 (10.8%) were African American/Black, 80 (1.5%) were Asian/Pacific Islander, and 8518 (78.5) were White. Of 65 US trials, 45 (69.2%) reported race and only 9 (13.8%) reported data on all 5 US racial categories. Of 286 global trials, 75 (26.2%) reported the enrollment proportion of older adults. Outcomes by race and age were reported in 2 (3.1%) and 41 (15.0%) trials, respectively. Black (EIR, 0.70; 95% CI, 0.59-0.83) and Hispanic (EIR, 0.70; 95% CI, 0.59-0.83) patients were significantly underrepresented in US trials. There was no disparity in older adult representation (TP, 21 143 [71.1%]; EIR, 1.00; 95% CI, 0.95-1.05). The representation of Black patients was lower in larger trials (meta-regression coefficient, -0.06; 95% CI, -0.10 to -0.02; P = .002).

Conclusions and Relevance

The results of this meta-analysis suggest that Black and Hispanic men are underrepresented in trials compared with their share of PCa incidence. The representation of Black patients has consistently remained low during the past 2 decades.

Racial disparities in prostate cancer among black men: epidemiology and outcomes

Prostate cancer has the widest racial disparities of any cancer, and these disparities appear at every stage of the cancer continuum. This review focuses on the disparities in prostate cancer between Black and White men, spanning from prevention and screening to clinical outcomes. We conduct an expansive review of the literature on racial disparities in prostate cancer, interpret the findings, and discuss areas of unmet need in research. We provide an overview of epidemiologic concepts necessary to understanding the current state of prostate cancer disparities, discuss the complexities of studying race, and review potential drivers of disparities in incidence and mortality. We argue that the cause of this disparity is multifactorial and due to a combination of social and environmental factors. The path forward needs to focus on enrolling and retaining Black men in prostate cancer clinical trials and observational studies and identifying potential interventions to improve prevention and clinical outcomes in Black men.

Characterization of Underrepresented Populations in Modern Era Clinical Trials Involving Radiation Therapy

PURPOSE

The demographic composition of modern radiation therapy (RT) clinical trials is incompletely studied. Understanding and minimizing disparities in clinical trials is critical to ensure health equity and the generalizability of research findings.

METHODS AND MATERIALS

Clinicaltrials.gov was searched to identify RT clinical trials that occurred from 1996 to 2019. A total of 1242 trials were reviewed for patient characteristics. The demographic composition of the studies was summarized by the frequency and percentage of patients by race, gender, and ethnicity. The racial composition of the study population was compared with the 2018 US Census using a 1-sample χ² test. Subgroup racial composition was compared using χ² tests of independence. Analyses used a complete case approach.

RESULTS

A total of 122 trials met the inclusion criteria, and 121 of these (99.1%) reported race. Trial subgroups included 63 trials in the United States (51.6%), 9 proton therapy trials (7.4%), 34 RT toxicity mitigation or prevention trials (27.9%), 24 trials for female cancer (19.7%), and 17 trials for male cancer (13.9%). US clinical trials overall, US RT toxicity mitigation or prevention trials, US trials for female cancer, and US trials for male cancer had significantly different racial compositions compared with the 2018 US Census data (P < .001 for all). Compared with all clinical trials, those for proton therapy had the largest magnitude of significantly lower enrollment of participants who identified their race as Black, Asian, or other (P < .001).

CONCLUSIONS

This study characterized the racial composition of prospective RT clinical trials in a modern cohort. The racial population represented across multiple categories in the United States differed significantly from US census data and was most pronounced in trials evaluating proton therapy. This is a benchmark study for future efforts to characterize and balance the participation of underrepresented populations in RT clinical trials.

Survival by race in men with chemotherapy-naive enzalutamide- or abiraterone-treated metastatic castration-resistant prostate cancer

BACKGROUND

Black men are more likely to be diagnosed with aggressive prostate cancer (PC) and die from PC than white men. However, black men with metastatic castration-resistant PC (mCRPC) had longer overall survival (OS) than white men when treated with certain agents in clinical trials. We analyzed claims data from the Veterans Health Administration (VHA) database to evaluate OS in black and white men treated with enzalutamide or abiraterone (novel hormonal therapy [NHT]) for chemotherapy-naïve mCRPC.

METHODS

Patients with mCRPC aged ≥18 years were identified in the VHA database by diagnosis codes, evidence of surgical/medical castration, and a prescription claim for enzalutamide or abiraterone after castration from April 2014-March 2017. Cox models assessed associations between race and OS. Unadjusted and multivariable analyses were performed on the entire population and subsets based on the type of therapy received (if any) after NHT.

RESULTS

In total, 2910 patients were identified (787 black, mean 71.7 years; 2123 white, mean 74.0 years). Median follow-up was 19.0 and 18.7 months in blacks and whites, respectively. Black men had better survival versus white men: hazard ratios (95% CIs) were 0.89 (0.790-0.996; P = 0.044) and 0.67 (0.592-0.758; P < 0.0001) in the unadjusted and multivariable models, respectively. Statistically significantly longer OS was seen in black versus white men regardless of subsequent treatment, including no subsequent treatment.

CONCLUSIONS

In the VHA, black men with chemotherapy-naïve mCRPC initiating NHT may have better outcomes than similarly treated white men.

PROMISE: a real-world clinical-genomic database to address knowledge gaps in prostate cancer

PURPOSE

Prostate cancer is a heterogeneous disease with variable clinical outcomes. Despite numerous recent approvals of novel therapies, castration-resistant prostate cancer remains lethal. A "real-world" clinical-genomic database is urgently needed to enhance our characterization of advanced prostate cancer and further enable precision oncology.

METHODS

The Prostate Cancer Precision Medicine Multi-Institutional Collaborative Effort (PROMISE) is a consortium whose aims are to establish a repository of de-identified clinical and genomic patient data that are linked to patient outcomes. The consortium structure includes a (1) bio-informatics committee to standardize genomic data and provide quality control, (2) biostatistics committee to independently perform statistical analyses, (3) executive committee to review and select proposals of relevant questions for the consortium to address, (4) diversity/inclusion committee to address important clinical questions pertaining to racial disparities, and (5) patient advocacy committee to understand patient perspectives to improve patients' quality of care.

RESULTS

The PROMISE consortium was formed by 16 academic institutions in early 2020 and a secure RedCap database was created. The first patient record was entered into the database in April 2020 and over 1000 records have been entered as of early 2021. Data entry is proceeding as planned with the goal to have over 2500 patient records by the end of 2021.

CONCLUSIONS

The PROMISE consortium provides a powerful clinical-genomic platform to interrogate and address data gaps that have arisen with increased genomic testing in the clinical management of prostate cancer. The dataset incorporates data from patient populations that are often underrepresented in clinical trials, generates new hypotheses to direct further research, and addresses important clinical questions that are otherwise difficult to investigate in prospective studies.

Racial differences in the treatment and outcomes for prostate cancer in Massachusetts

BACKGROUND

Massachusetts is a northeastern state with universally mandated health insurance since 2006. Although Black men have generally worse prostate cancer outcomes, emerging data suggest that they may experience equivalent outcomes within a fully insured system. In this setting, the authors analyzed treatments and outcomes of non-Hispanic White and Black men in Massachusetts.

METHODS

White and Black men who were 20 years old or older and had been diagnosed with localized intermediate- or high-risk nonmetastatic prostate cancer in 2004-2015 were identified in the Massachusetts Cancer Registry. Adjusted logistic regression models were used to assess predictors of definitive therapy. Adjusted and unadjusted survival models compared cancer-specific mortality. Interaction terms were then used to assess whether the effect of race varied between counties.

RESULTS

A total of 20,856 men were identified. Of these, 19,287 (92.5%) were White. There were significant county-level differences in the odds of receiving definitive therapy and survival. Survival was worse for those with high-risk cancer (adjusted hazard ratio [HR], 1.50; 95% CI, 1.4-1.60) and those with public insurance (adjusted HR for Medicaid, 1.69; 95% CI, 1.38-2.07; adjusted HR for Medicare, 1.2; 95% CI, 1.14-1.35). Black men were less likely to receive definitive therapy (adjusted odds ratio, 0.78; 95% CI, 0.74-0.83) but had a 17% lower cancer-specific mortality (adjusted HR, 0.83; 95% CI, 0.7-0.99).

CONCLUSIONS

Despite lower odds of definitive treatment, Black men experience decreased cancer-specific mortality in comparison with White men in Massachusetts. These data support the growing body of research showing that Black men may achieve outcomes equivalent to or even better than those of White men within the context of a well-insured population.

LAY SUMMARY

There is a growing body of evidence showing that the excess risk of death among Black men with prostate cancer may be caused by disparities in access to care, with few or no disparities seen in universally insured health systems such as the Veterans Affairs and US Military Health System. Therefore, the authors sought to assess racial disparities in prostate cancer in Massachusetts, which was the earliest US state to mandate universal insurance coverage (in 2006). Despite lower odds of definitive treatment, Black men with prostate cancer experience reduced cancer-specific mortality in comparison with White men in Massachusetts. These data support the growing body of research showing that Black men may achieve outcomes equivalent to or even better than those of White men within the context of a well-insured population.

Evolution of Disparities in Prostate Cancer Treatment: Is This a New Normal?

Despite notable screening, diagnostic, and therapeutic advances, disparities in prostate cancer incidence and outcomes remain prevalent. Although commonly discussed in the context of men of African descent, disparities also exist based on socioeconomic level, education level, and geographic location. The factors in these disparities span systemic access issues affecting availability of care, provider awareness, and personal patient views and mistrust. In this review, we will discuss common themes that patients have noted as impediments to care. We will review how equitable access to care has helped improve outcomes among many different groups of patients, including those with local disease and those with metastatic castration-resistant prostate cancer. Even with more advanced presentation, challenges with recommended screening, and lower rates of genomic testing and trial inclusion, Black populations have benefited greatly from various modalities of therapy, achieving comparable and at times superior outcomes with certain types of immunotherapy, chemotherapy, androgen receptor-based inhibitors, and radiopharmaceuticals in advanced disease. We will also briefly discuss access to genomic testing and differences in patterns of gene expression among Black patients and other groups that are traditionally underrepresented in trials and genomic cohort studies. We propose several strategies on behalf of providers and institutions to help promote more equitable care access environments and continued decreases in prostate cancer disparities across many subgroups.

Lack of Racial Survival Differences in Metastatic Prostate Cancer in National Cancer Data Base (NCDB): A Different Finding Compared to Non-metastatic Disease

Background: Inconsistent findings have been reported in the literature regarding racial differences in survival outcomes between African American and white patients with metastatic prostate cancer (mPCa). The current study utilized a national database to determine whether racial differences exist among the target population to address this inconsistency.

Methods: This study retrospectively reviewed prostate cancer (PCa) patient data (N = 1,319,225) from the National Cancer Database (NCDB). The data were divided into three groupings based on the metastatic status: (1) no metastasis (N = 318,291), (2) bone metastasis (N = 29,639), and (3) metastases to locations other than bone, such as brain, liver, or lung (N = 952). Survival probabilities of African American and white PCa patients with bone metastasis were examined through parametric proportional hazards Weibull models and Bayesian survival analysis. These results were compared to patients with no metastasis or other types of metastases.

Results: No statistically supported racial disparities were observed for African American and white men with bone metastasis (p = 0.885). Similarly, there were no racial disparities in survival for those men suffering from other metastases (liver, lung, or brain). However, racial disparities in survival were observed among the two racial groups with non-metastatic PCa (p < 0.001) or when metastasis status was not taken into account (p < 0.001). The Bayesian analysis corroborates the finding.

Conclusion: This research supports our previous findings and shows that there are no racial differences in survival outcomes between African American and white patients with mPCa. In contrast, racial disparities in the survival outcome continue to exist among non-metastatic PCa patients. Further research is warranted to explain this difference.

Androgen receptor with short polyglutamine tract preferably enhances Wnt/β-catenin-mediated prostatic tumorigenesis

Polyglutamine (polyQ) tract polymorphism within the human androgen receptor (AR) shows population heterogeneity. African American men possess short polyQ tracts significantly more frequently than Caucasian American men. The length of polyQ tracts is inversely correlated with the risk of prostate cancer, age of onset, and aggressiveness at diagnosis. Aberrant activation of Wnt signaling also reveals frequently in advanced prostate cancer, and an enrichment of androgen and Wnt signaling activation has been observed in African American patients. Here, we assessed aberrant expression of AR bearing different polyQ tracts and stabilized β-catenin in prostate tumorigenesis using newly generated mouse models. We observed an early onset oncogenic transformation, accelerated tumor cell growth, and aggressive tumor phenotypes in the compound mice bearing short polyQ tract AR and stabilized β-catenin. RNA sequencing analysis showed a robust enrichment of Myc-regulated downstream genes in tumor samples bearing short polyQ AR versus those with longer polyQ tract AR. Upstream regulator analysis further identified Myc as the top candidate of transcriptional regulators in tumor cells from the above mouse samples with short polyQ tract AR and β-catenin. Chromatin immunoprecipitation analyses revealed increased recruitment of β-catenin and AR on the c-Myc gene regulatory locus in the tumor tissues expressing stabilized β-catenin and shorter polyQ tract AR. These data demonstrate a promotional role of aberrant activation of Wnt/β-catenin in combination with short polyQ AR expression in prostate tumorigenesis and suggest a potential mechanism underlying aggressive prostatic tumor development, which has been frequently observed in African American patients.

Association of Black Race With Prostate Cancer-Specific and Other-Cause Mortality

Importance

Black men are more likely to die of prostate cancer than white men. In men with similar stages of disease, the contribution of biological vs nonbiological differences to this observed disparity is unclear.

Objective

To quantify the association of black race with long-term survival outcomes after controlling for known prognostic variables and access to care among men with prostate cancer.

Design, Setting, and Participants

This multiple-cohort study included updated individual patient-level data of men with clinical T1-4N0-1M0 prostate cancer from the following 3 cohorts: Surveillance, Epidemiology, and End Results (SEER [n = 296 273]); 5 equal-access regional medical centers within the Veterans Affairs health system (VA [n = 3972]); and 4 pooled National Cancer Institute-sponsored Radiation Therapy Oncology Group phase 3 randomized clinical trials (RCTs [n = 5854]). Data were collected in the 3 cohorts from January 1, 1992, through December 31, 2013, and analyzed from April 27, 2017, through April 13, 2019.

Exposures

In the VA and RCT cohorts, all patients received surgery and radiotherapy, respectively, with curative intent. In SEER, radical treatment, hormone therapy, or conservative management were received.

Main Outcomes and Measures

Prostate cancer-specific mortality (PCSM). Secondary measures included other-cause mortality (OCM). To adjust for demographic-, cancer-, and treatment-related baseline differences, inverse probability weighting (IPW) was performed.

Results

Among the 306 100 participants included in the analysis (mean [SD] age, 64.9 [8.9] years), black men constituted 52 840 patients (17.8%) in the SEER cohort, 1513 (38.1%) in the VA cohort, and 1129 (19.3%) in the RCT cohort. Black race was associated with an increased age-adjusted PCSM hazard (subdistribution hazard ratio [sHR], 1.30; 95% CI, 1.23-1.37; P < .001) within the SEER cohort. After IPW adjustment, black race was associated with a 0.5% (95% CI, 0.2%-0.9%) increase in PCSM at 10 years after diagnosis (sHR, 1.09; 95% CI, 1.04-1.15; P < .001), with no significant difference for high-risk men (sHR, 1.04; 95% CI, 0.97-1.12; P = .29). No significant differences in PCSM were found in the VA IPW cohort (sHR, 0.85; 95% CI, 0.56-1.30; P = .46), and black men had a significantly lower hazard in the RCT IPW cohort (sHR, 0.81; 95% CI, 0.66-0.99; P = .04). Black men had a significantly increased hazard of OCM in the SEER (sHR, 1.30; 95% CI, 1.27-1.34; P < .001) and RCT (sHR, 1.17; 95% CI, 1.06-1.29; P = .002) IPW cohorts.

Conclusions and Relevance

In this study, after adjustment for nonbiological differences, notably access to care and standardized treatment, black race did not appear to be associated with inferior stage-for-stage PCSM. A large disparity remained in OCM for black men with nonmetastatic prostate cancer.

Does race predict the development of metastases in men who receive androgen-deprivation therapy for a biochemical recurrence after radical prostatectomy?

BACKGROUND

In this study among men who underwent radical prostatectomy (RP), African American men (AAM) were 28% more likely to develop recurrent disease compared with Caucasian men (CM). However, among those who had nonmetastatic, castration-resistant prostate cancer (CRPC), race did not predict metastases or overall survival. Whether race predicts metastases among men who receive androgen-deprivation therapy (ADT) after a biochemical recurrence (BCR) (ie, before CRPC but after BCR) is untested.

METHODS

The authors identified 595 AAM and CM who received ADT for a BCR that developed after RP between 1988 and 2015 in the Shared Equal-Access Regional Cancer Hospital (SEARCH) database. Univariable and multivariable Cox models were used to test the association between race and the time from ADT to metastases. Secondary outcomes included the time to CRPC, all-cause mortality, and prostate cancer-specific mortality.

RESULTS

During a median follow-up of 66 months after ADT, 62 of 354 CM (18%) and 38 of 241 AAM (16%) developed metastases. AAM were younger at the time they received ADT (63 vs 67 years; P < .001), had received ADT in a more recent year (2008 vs 2006; P < .001), had higher prostate-specific antigen levels at RP (11.1 vs 9.2 ng/mL; P < .001), lower pathologic Gleason scores (P = .004), and less extracapsular extension (38% vs 48%; P = .022). On multivariable analysis, there was no association between race and metastases (hazard radio, 1.20; P = .45) or any of the other secondary outcomes (all P > .5).

CONCLUSIONS

Among veterans who received ADT post-BCR after RP, race was not a predictor of metastases or other adverse outcomes. The current findings suggest that research efforts to understand racial differences in prostate cancer biology should focus on early stages of the disease (ie, closer to the time of diagnosis).

Prostate-specific antigen response in black and white patients treated with abiraterone acetate for metastatic castrate-resistant prostate cancer

PURPOSE

Evidence suggests differences in androgen receptor AR signaling between black (B) and white (W) patients with prostate cancer, but pivotal trials of abiraterone acetate (AA) for patients with metastatic castration-resistant prostate cancer (mCRPC) enrolled few black patients, a population with a higher mortality from prostate cancer. Our primary objective was to determine differences in response to AA between B and W patients.

METHODS

We performed a retrospective case-control study of B vs. W patients treated with AA between May 1, 2008 and June 16, 2015 at Duke University Medical Center. Patients were identified (W control patients were matched 2:1 to B patients stratified based on previous docetaxel exposure) through pharmacy records and were eligible if treated with AA for metastatic castration-resistant prostate cancer. Patients with previous enzalutamide use were excluded. The primary objective was to compare the rate of≥90% prostate-specific antigen (PSA) decline from baseline between B vs. W patients. Secondary outcomes included comparing time on therapy, time to PSA progression, and overall survival among groups.

RESULTS

Baseline characteristics among patients (n = 45 B, n = 90 W) were identified; these included Karnofsky performance status, PSA, Gleason score, alkaline phosphatase, albumin, hemoglobin, lactate dehydrogenase, opiate use for pain, and metastatic sites. Baseline characteristics among groups were similar except for median hemoglobin (B = 11.4g/dl, W = 12.3g/dl). The proportion of B patients achieving a≥90% PSA level decline was 37.8% vs. 28.9% for W patients (P = 0.296). Statistically significant differences were found in the proportion of patients achieving a≥50% PSA level decline (B = 68.9%, W = 48.9% [P = 0.028]) and≥30% PSA level decline (B = 77.8%, W = 54.4% [P = 0.008]). Rates of primary abiraterone-refractory disease (PSA increase as best response) trended higher in W (31.1%) than in B (15.6%) patients (P = 0.052). Median treatment duration (B = 9.4 mo, W = 8.3 mo) did not differ (Wilcoxon P = 0.444). Median overall survival (B = 27.3 mo [95% CI: 13.9, not estimable], W = 24.8 mo [95% CI: 19, 31.6] [P = 0.669]) and median time to PSA progression (B = 11.0 mo [95% CI: 4.3, 18.0], W = 9.4 mo [95% CI: 6.2, 13.0] [P = 0.917]) did not differ.

CONCLUSIONS

Black patients may have a higher PSA response to AA than white patients. An ongoing prospective clinical study (NCT01940276) is evaluating outcomes between black and white patients treated with AA.