Re-examining racial disparities in prostate cancer outcomes

Prostate Cancer Disparities and Management in Southern Africa: Insights into Practices, Norms and Values

Prostate cancer (PCa) is a leading cause of mortality in men of African origin. While men of African descent in high-income countries (HICs) demonstrate poor prognosis compared to their European counterparts, African men on the African continent, particularly Southern Africa have shown even higher PCa mortality rates. Extrinsic factors such as the socioeconomic status, education level, income level, geographic location and race contribute to PCa patient outcome. These are further deepened by the African norms which are highly esteemed and may have detrimental effects on PCa patients' health. Insights into African cultures and social constructs have been identified as key elements towards improving men's health care seeking behaviour which will in turn improve PCa patients' outcome. Compared to Southern Africa, the Eastern, Western and Central African regions have lower PCa incidence rates but higher mortality rates. The availability of cancer medical equipment has also been reported to be disproportionate in Africa, with most cancer resources in Northern and Southern Africa. Even within Southern Africa, cancer management resources are unevenly available where one country must access PCa specialised care in the neighbouring countries. While PCa seems to be better managed in HICs, steps towards effective PCa management are urgently needed in Africa, as this continent represents a significant portion of low-middle-income countries (LMICs). Replacing African men in Africa with African American men may not optimally resolve PCa challenges in Africa. Adopting western PCa management practices can be optimised by integrating improved core-African norms. The aim of this review is to discuss PCa disparities in Africa, deliberate on the significance of integrating African norms around masculinity and discuss challenges and opportunities towards effective PCa care in Africa, particularly in Southern Africa.

Trends in the use of active surveillance and treatments in Medicare beneficiaries diagnosed with localized prostate cancer

BACKGROUND

The treatment for men diagnosed with localized prostate cancer has changed over time given the increased attention to the harms associated with over-diagnosis and the development of protocols for active surveillance.

METHODS

We examined trends in the treatment of men diagnosed with localized prostate cancer between 2004 and 2015, using the most recently available data from Surveillance, Epidemiology, and End Results Program (SEER)-Medicare. Patients were stratified by Gleason score, age, and race groups.

RESULTS

The use of active surveillance increased from 22% in 2004-2005 to 50% in 2014-2015 for patients with a Gleason score of 6 or below and increased from 9% in 2004-2005 to 13% in 2014-2015 for patients with a Gleason score of 7 or above. Patients with a Gleason score of 7 or above had increased use of intensity-modulated radiation therapy and prostatectomy, especially among patients aged 75 years and older. Among patients with a Gleason score of 6 or below non-Hispanic black men were less likely to undergo active surveillance than non-Hispanic white men.

CONCLUSIONS

There has been a large increase in the use of active surveillance among men with a Gleason score of 6 or below. However, non-Hispanic black men with a Gleason score of 6 or below are less likely to receive active surveillance.

Clinical outcomes in men of diverse ethnic backgrounds with metastatic castration-resistant prostate cancer

BACKGROUND

We have shown previously in multivariable analysis that black men had 19% lower risk of death than white men with metastatic castration-resistant prostate cancer (mCRPC) treated with a docetaxel and prednisone (DP)-based regimen. The primary goal of this analysis was to compare progression-free survival (PFS), biochemical PFS, ≥50% decline in prostate-specific antigen (PSA) from baseline and objective response rate (ORR) in white, black and Asian men with mCRPC treated with a DP-based regimen.

PATIENTS AND METHODS

Individual patient data from 8820 mCRPC men randomized on nine phase III trials to a DP-containing regimen were combined. Race used in the analysis was based on self-report. End points were PFS, biochemical PSA, ≥50% decline in PSA from baseline and ORR. The proportional hazards and the logistic regression models were employed to assess the prognostic importance of race in predicting outcomes adjusting for established prognostic factors.

RESULTS

Of 8820 patients, 7528 (85%) were white, 500 (6%) were black, 424 were Asian (5%) and 368 (4%) had race unspecified. Median PFS were 8.3 [95% confidence interval (CI) 8.2-8.5], 8.2 (95% CI 7.4-8.8) and 8.3 (95% CI 7.6-8.8) months in white, black and Asian men, respectively. Median PSA PFS were 9.9 (95% CI 9.7-10.4), 8.5 (95% CI 8.0-10.3) and 11.1 (95% CI 9.9-12.5) months in white, black and Asian men, respectively.

CONCLUSIONS

We observed no differences in clinical outcomes by race and ethnic groups in men with mCRPC enrolled on these phase III clinical trials with DP.

Putting Evidence Academies into action: Prostate cancer, nutrition, and tobacco control science

A well-documented challenge in moving public health research into practice is the extended time it takes to implement findings in clinical practice and communities. The Evidence Academy model (Rohweder et al., 2016), developed and first used in North Carolina, is a pragmatic, action-oriented model that aims to shorten this timeline by communicating cutting-edge findings directly to those who can use them and convening individuals working in a single topic area to network and plan activities for the future. The University of Pennsylvania Collaborating Center of the Cancer Prevention and Control Research Network (CPCRN) held three conferences based on the Evidence Academy model: one about prostate cancer in 2015, a second on food access and obesity prevention in 2017, and a third about tobacco control science in 2018. A diverse planning committee of stakeholders helped shape the content, focus,and format of each conference. Local and national experts presented findings to regional audiences of researchers, practitioners, government leaders, and community members. Each Evidence Academy included collaborators and speakers from other Prevention Research Centers (PRCs) and CPCRN network sites. Evaluations and outcomes indicated that the events were successful in achieving their goals and fostered ongoing relationships among attendees. This paper illustrates how the Evidence Academy model was used in a different region and describes lessons learned and follow-up activities that were initiated via the Evidence Academy and with input from participants. Lessons learned may be helpful in developing and evaluating future adaptations of the Evidence Academy model and/or the effectiveness of its components.

Associação de variáveis sociodemográficas e clínicas com os tempos para início do tratamento do câncer de próstata

Resumo Disparidades na atenção ao câncer de próstata têm sido reveladas e associadas a fatores sociodemográficos e clínicos, os quais determinam os tempos para diagnóstico e início do tratamento. O objetivo deste artigo é avaliar a associação de variáveis sociodemográficas e clínicas com os tempos para o início do tratamento do câncer de próstata. Estudo de coorte longitudinal prospectivo utilizando dados secundários, cuja população é de homens com câncer de próstata atendidos nos períodos de 2010-2011 e 2013-2014 no Hospital Santa Rita de Cássia, Vitória, Espírito Santo, Brasil. A população do estudo foi de 1.388 homens, do total, os com idade inferior a 70 anos (OR = 1,85; IC = 1,49-2,31), não brancos (OR = 1,30; IC = 1,00-1,70), com menos de oito anos de estudo (OR = 1,52; IC = 1,06-2,17) e encaminhados pelos serviços do Sistema Único de Saúde (OR = 2,52; IC = 1,84-3,46) apresentaram maior risco de atraso no tratamento. Da mesma forma, quanto menor o escore de Gleason (OR = 1,78; IC = 1,37-2,32) e os níveis de Antígeno Prostático Específico (OR = 2,71; IC = 2,07-3,54) maior a probabilidade de atraso para iniciar o tratamento. Portanto, as características sociodemográficas e clínicas exerceram uma forte influência no acesso ao tratamento do câncer de próstata.

A Novel FGFR3 Splice Variant Preferentially Expressed in African American Prostate Cancer Drives Aggressive Phenotypes and Docetaxel Resistance

Alternative splicing (AS) has been shown to participate in prostate cancer development and progression; however, a link between AS and prostate cancer health disparities has been largely unexplored. Here we report on the cloning of a novel splice variant of FGFR3 that is preferentially expressed in African American (AA) prostate cancer. This novel variant (FGFR3-S) omits exon 14, comprising 123 nucleotides that encode the activation loop in the intracellular split kinase domain. Ectopic overexpression of FGFR3-S in European American (EA) prostate cancer cell lines (PC-3 and LNCaP) led to enhanced receptor autophosphorylation and increased activation of the downstream signaling effectors AKT, STAT3, and ribosomal S6 compared with FGFR3-L (retains exon 14). The increased oncogenic signaling imparted by FGFR3-S was associated with a substantial gain in proliferative and antiapoptotic activities, as well as a modest but significant gain in cell motility. Moreover, the FGFR3-S-conferred proliferative and motility gains were highly resistant to the pan-FGFR small-molecule inhibitor dovitinib and the antiapoptotic gain was insensitive to the cytotoxic drug docetaxel, which stands in marked contrast with dovitinib- and docetaxel-sensitive FGFR3-L. In an in vivo xenograft model, mice injected with PC-3 cells overexpressing FGFR3-S exhibited significantly increased tumor growth and resistance to dovitinib treatment compared with cells overexpressing FGFR3-L. In agreement with our in vitro and in vivo findings, a high FGFR3-S/FGFR3-L expression ratio in prostate cancer specimens was associated with poor patient prognosis. IMPLICATIONS: This work identifies a novel FGFR3 splice variant and supports the hypothesis that differential AS participates in prostate cancer health disparities.

Role of Alternative Splicing in Prostate Cancer Aggressiveness and Drug Resistance in African Americans

Alternative splicing, the process of removing introns and joining exons of pre-mRNA, is critical for growth, development, tissue homeostasis, and species diversity. Dysregulation of alternative splicing can initiate and drive disease. Aberrant alternative splicing has been shown to promote the "hallmarks of cancer" in both hematological and solid cancers. Of interest, recent work has focused on the role of alternative splicing in prostate cancer and prostate cancer health disparities. We will provide a review of prostate cancer health disparities involving the African American population, alternative RNA splicing, and alternative splicing in prostate cancer. Lastly, we will summarize our work on differential alternative splicing in prostate cancer disparities and its implications for disparate health outcomes and therapeutic targets.

Exogenous IL-6 induces mRNA splice variant MBD2_v2 to promote stemness in TP53 wild-type, African American PCa cells

African American men (AAM) are at higher risk of being diagnosed with prostate cancer (PCa) and are at higher risk of dying from the disease compared to European American men (EAM). We sought to better understand PCa molecular diversity that may be underlying these disparities. We performed RNA‐sequencing analysis on high‐grade PCa to identify genes showing differential tumor versus noncancer adjacent tissue expression patterns unique to AAM or EAM. We observed that interleukin‐6 (IL‐6) was upregulated in the nonmalignant adjacent tissue in AAM, but in EAM IL‐6 expression was higher in PCa tissue. Enrichment analysis identified that genes linked to the function of TP53 were overrepresented and downregulated in PCa tissue from AAM. These RNA‐sequencing results informed our subsequent investigation of a diverse PCa cell line panel. We observed that PCa cell lines that are TP53 wild‐type, which includes cell lines derived from AAM (MDA‐PCa‐2b and RC77T), did not express detectable IL‐6 mRNA. IL‐6 treatment of these cells downregulated wild‐type TP53 protein and induced mRNA and protein expression of the epigenetic reader methyl CpG binding domain protein 2 (MBD2), specifically the alternative mRNA splicing variant MBD2_v2. Further investigation validated that upregulation of this short isoform promotes self‐renewal and expansion of PCa cancer stem‐like cells (CSCs). In conclusion, this report contributes to characterizing gene expression patterns in high‐grade PCa and adjacent noncancer tissues from EAM and AAM. The results we describe here advance what is known about the biology associated with PCa race disparities and the molecular signaling of CSCs.

Profiles of miRNA Isoforms and tRNA Fragments in Prostate Cancer

MicroRNA (miRNA) isoforms (“isomiRs”) and tRNA-derived fragments (“tRFs”) are powerful regulatory non-coding RNAs (ncRNAs). In human tissues, both types of molecules are abundant, with expression patterns that depend on a person’s race, sex and population origin. Here, we present our analyses of the Prostate Cancer (PRAD) datasets of The Cancer Genome Atlas (TCGA) from the standpoint of isomiRs and tRFs. This study represents the first simultaneous examination of isomiRs and tRFs in a large cohort of PRAD patients. We find that isomiRs and tRFs have extensive correlations with messenger RNAs (mRNAs). These correlations are disrupted in PRAD, which suggests disruptions of the regulatory network in the disease state. Notably, we find that the profiles of isomiRs and tRFs differ in patients belonging to different races. We hope that the presented findings can lay the groundwork for future research efforts aimed at elucidating the functional roles of the numerous and distinct members of these two categories of ncRNAs that are present in PRAD.

Epigenetic basis of cancer health disparities: Looking beyond genetic differences

Despite efforts at various levels, racial health disparities still exist in cancer patients. These inequalities in incidence and/or clinical outcome can only be explained by a multitude of factors, with genetic basis being one of them. Several investigations have provided convincing evidence to support epigenetic regulation of cancer-associated genes, which results in the differential transcriptome and proteome, and may be linked to a pre-disposition of individuals of certain race/ethnicity to early or more aggressive cancers. Recent technological advancements and the ability to quickly analyze whole genome have aided in these efforts, and owing to their relatively easy detection, methylation events are much well-characterized, than the acetylation events, across human populations. The early trend of investigating a pre-determined set of genes for differential epigenetic regulation is paving way for more unbiased screening. This review summarizes our current understanding of the epigenetic events that have been tied to the racial differences in cancer incidence and mortality. A better understanding of the epigenetics of racial diversity holds promise for the design and execution of novel strategies targeting the human epigenome for reducing the disparity gaps.

Racial disparities in prostate cancer: a molecular perspective

Prostate cancer incidence and mortality rates are remarkably higher in African-American men as compared to their European-Americans counterparts. Despite these recognitions, precise causes underlying such prevalent racial disparities remain poorly understood. Although socioeconomic factors could account for such differences up to a certain extent, it is now being increasingly realized that such disparity has a molecular basis. Indeed, several differences, including genetic polymorphism, gene mutations, epigenetic modifications, miRNAs alterations, etc., have been reported in malignant prostate tissues from patients of diverse racial backgrounds. Here, we attempt to provide a molecular perspective on prostate cancer racial disparities by gathering available information on these associated factors and discussing their potential significance in disproportionate incidence and clinical outcomes.

Impact of treatment on progression to castration-resistance, metastases, and death in men with localized high-grade prostate cancer

Men with high‐grade prostate cancer (HGPC) are at greatest risk of disease progression. Clinical risk factors associated with castration‐resistant prostate cancer (CRPC), metastases, and prostate cancer‐specific mortality (PCSM) were identified in a contemporary HGPC cohort. Clinical data was collected from men diagnosed with Gleason sum (GS) ≥8 at the Greater Los Angeles Veterans Affairs (GLA‐VA) Healthcare System between 2000 and 2013. Multivariable competing risks regression analyses assessed progression to CRPC, metastases, and PCSM within three treatment strata. The cumulative incidence of disease progression was calculated at 2, 5, and 10‐year time points. Review of 2149 prostate cancer cases yielded 322 with HGPC. Median survival times for cancer‐specific and overall mortality were significantly shorter in men treated with primary androgen deprivation therapy (ADT) (P = 0.0002 and P < 0.0001). Multivariable analyses revealed that clinical stage N1, GS 10, and treatment with primary ADT were significantly associated with increased risk of CRPC, metastases, and PCSM. Significant differences in these outcomes were not observed in men treated with radical prostatectomy (RP) when compared to those treated with radiation therapy combined with short‐term ADT (XRT‐ADT). Ten‐year event rates of progression to CRPC, metastases, and PCSM, for men treated with primary ADT, were 45.5%, 25.4%, and 25.1%, respectively. In conclusion, GS 10 and lymph node involvement, as well as primary ADT treatment in men with HGPC was associated with increased risk of CRPC, metastases, and PCSM. Curative‐intent treatment with RP or XRT‐ADT is associated with reduced progression rates and death in men with HGPC.

Sociodemographic and Clinical Predictors of Switching to Active Treatment among a Large, Ethnically Diverse Cohort of Men with Low Risk Prostate Cancer on Observational Management

PURPOSE

We determined the clinical and sociodemographic predictors of beginning active treatment in an ethnically diverse population of men with low risk prostate cancer initially on observational treatment.

MATERIALS AND METHODS

We retrospectively studied men diagnosed with low risk prostate cancer between 2004 and 2012 at Kaiser Permanente Northern California who did not receive any treatment within the first year of diagnosis and had at least 2 years of followup. We used Cox proportional hazards regression models to determine factors associated with time from diagnosis to active treatment.

RESULTS

We identified 2,228 eligible men who were initially on observation, of whom 27% began active treatment during followup at a median of 2.9 years. NonHispanic black men were marginally more likely to begin active treatment than nonHispanic white men independent of baseline and followup clinical measures (HR 1.3, 95% CI 1.0-1.7). Among men who remained on observation nonHispanic black men were rebiopsied within 24 months of diagnosis at a slightly lower rate than nonHispanic white men (HR 0.70, 95% CI 0.6-1.0). Gleason grade progression (HR 3.3, 95% CI 2.7-4.1) and PSA doubling time less than 48 months (HR 2.9, 95% CI 2.3-3.7) were associated with initiation of active treatment independent of race.

CONCLUSIONS

Sociodemographic factors such as ethnicity and education may independently influence the patient decision to pursue active treatment and serial biopsies during active surveillance. These factors are important for further studies of prostate cancer treatment decision making.

African American Participation in Oncology Clinical Trials--Focus on Prostate Cancer: Implications, Barriers, and Potential Solutions

In the United States, the incidence and mortality rates of many cancers, especially prostate cancer, are disproportionately high among African American men compared with Caucasian men. Recently, mortality rates for prostate cancer have declined more rapidly in African American versus Caucasian men, but prostate cancer is still the most common cancer and the second leading cause of cancer deaths in African American men in the United States. Compared with Caucasian men, prostate cancer occurs at younger ages, has a higher stage at diagnosis, and is more likely to progress after definitive treatments in African American men. Reasons for racial discrepancies in cancer are multifactorial and potentially include socioeconomic, cultural, nutritional, and biologic elements. In addition to improving access to novel therapies, clinical trial participation is essential to adequately establish the risks and benefits of treatments in African American populations. Considering the disproportionately high mortality rates noted in these groups, our understanding of the natural history and responses to therapies is limited. This review will explore African American underrepresentation in clinical trials with a focus on prostate cancer, and potentially effective strategies to engage African American communities in prostate cancer research. Solutions targeting physicians, investigators, the community, and health care systems are identified. Improvement of African American participation in prostate cancer clinical trials will benefit all stakeholders.

Association between very small tumour size and increased cancer-specific mortality after radical prostatectomy in lymph node-positive prostate cancer

OBJECTIVE

To determine whether very small prostate cancers present in patients who also have lymph node (LN) metastases represent a particularly aggressive disease variant compared with larger LN-positive tumours.

PATIENTS AND METHODS

We identified 37 501 patients diagnosed with prostate cancer between 1988 and 2001 treated with radical prostatectomy within the Surveillance, Epidemiology, and End Results database. The primary study variables were tumour size by largest dimension (stratified into: (i) microscopic focus only or 1 mm; (ii) 2-15 mm; (iii) 16-30 mm; (iv) >30 mm), regional LN involvement, and the corresponding interaction term. We evaluated the risk of 10-year prostate cancer-specific mortality (PCSM) using the Fine and Gray model for competing risks after controlling for race, tumour grade, T stage, receipt of radiation, number of dissected LNs, number of positive LNs, year of diagnosis, and age at diagnosis.

RESULTS

The median follow-up was 11.8 years. There was a significant interaction between tumour size and LN involvement (P-interaction <0.001). In the absence of LN involvement (36 561 patients), the risk of 10-year PCSM increased monotonically with increasing tumour size. Among patients with LN involvement (940), those with the smallest tumours had increased 10-year PCSM compared with patients with tumours sized 2-15 mm (24.7% vs 11.8%; adjusted hazard ratio [AHR] 2.84, 95% confidence interval [CI] 1.21-6.71; P = 0.017) or 16-30 mm (24.7% vs 15.5%; AHR 3.12, 95% CI 1.51-6.49; P = 0.002), and similar 10-year PCSM as those with tumours >30 mm (24.7% vs 24.9%; P = 0.156).

CONCLUSION

In patients with prostate cancer with LN involvement, very small tumour size may predict for higher PCSM compared with some larger tumours, even after controlling for other prognostic variables. These tumours might be particularly aggressive, beyond what is captured by pathological assessment of tumour grade and stage.