Prostate tumors of native men from West Africa show biologically distinct pathways-A comparative genomic study

BACKGROUND

Native African men (NAM) experience a disproportionate burden of prostate cancer (PCa) and have higher mortality rates compared to European American men (EAM). While socioeconomic status has been implicated as a driver of this disparity, little is known about the genomic mechanisms and distinct biological pathways that are associated with PCa of native men of African origin.

METHODS

To understand biological factors that contribute to this disparity we utilized a total of 406 multi-institutional localized PCa samples, collected by Men of African Descent and Carcinoma of the Prostate biospecimen network and Moffitt Cancer Center/University of Pennsylvania Health science system. We performed comparative genomics and immunohistochemistry to identify the biomarkers that are highly enriched in NAM from west Africa and compared them with African American Men (AAM) and EAM. Quantified messenger RNA expression and Median H scores based on immune reactivity of staining cells, were compared using Mann Whitney test. For gene expression analysis, p values were further adjusted for multiple comparisons using false discovery rates.

RESULTS

Immunohistochemical analysis on selected biomarkers showed a consistent association between ETS related gene (ERG) status and race with 83% of NAM exhibiting tumors that lacked TMPRSS2-ERG translocation (ERG^negative ) as compared to AAM (71%) and EAM (52%). A higher proportion of NAM (29%) were also found to be double negative (ERG^negative and PTEN^Loss ) as compared to AAM (6%) and EAM (7%). NAM tumors had significantly higher immunoreactivity (H-score) for PSMA, and EZH2, whereas they have lower H-score for PTEN, MYC, AR, RB and Racemase, (all p < .05). Comparative genomics revealed that NAM had significant transcriptomic variability in AR-activity score. In pathways enrichment analysis NAM tumors exhibited the enrichment of proinflammatory pathways including cytokine, interleukins, inflammatory response, and nuclear factor kappa B signaling.

CONCLUSIONS

Prostate tumors in NAM are genomically distinct and are characterized by the dysregulation of several biomarkers. Furthermore, these tumors are also highly enriched for the major proinflammatory pathways. These distinct biological features may have implications for diagnosis and response to targeted therapy among Black men, globally.

Contemporary Radiation Treatment of Prostate Cancer in Africa: A Ghanaian Experience

Purpose

Data on prostate cancer (PCa) treatment in Africa remains under-reported. We present a review of the management of PCa at the cancer center of the largest tertiary referral facility in Ghana, with emphasis on curative treatment.

Methods

We retrospectively reviewed data on 1,074 patients seen at the National Center for Radiotherapy and Nuclear Medicine from 2003 to 2016. Patient and disease characteristics at presentation are presented using descriptive statistics. The χ² and Fisher’s exact tests and Mann-Whitney U test were used to analyze differences between categorical and continuous variables, respectively. Methods of survival analysis were used to evaluate the relative risk of biochemical disease-free survival (bDFS).

Results

Seventy percent of the study population presented with localized disease. High-risk disease presentation accounted for 64.4% of these patients. Only 57.6% of patients with localized disease received curative radiotherapy. The 5-year overall survival for the curative cohort was 96% (interquartile range, 93% to 98%). The 5-year bDFS rates for low-, intermediate-, and high-risk groups were 95%, 70%, and 48%, respectively. Both Gleason score and pretreatment prostate-specific antigen were significant predictors for bDFS in multivariable analysis.

Conclusion

We show that the majority of patients with PCa have locally advanced disease at the time of presentation for radiotherapy. bDFS was significantly better for low- and intermediate-risk than for high-risk disease. These data emphasize the dire need to re-evaluate screening and patient education of PCa in regions of the world with high incidence and mortality as well as the need for improved access to care and treatment delivery.

Optimizing Time to Treatment to Achieve Durable Biochemical Disease Control after Surgery in Prostate Cancer: A Multi-Institutional Cohort Study

BACKGROUND

The impact of treatment delays on prostate cancer-specific outcomes remains ill-defined. This study investigates the effect of time to treatment on biochemical disease control after prostatectomy.

METHODS

This retrospective study includes 1,807 patients who received a prostatectomy as a primary treatment at two large tertiary referral centers from 1987 to 2015. Multivariate cox model with restricted cubic spline was used to identify optimal time to receive treatment and estimate the risk of biochemical recurrence.

RESULTS

Median follow-up time of the study was 46 (interquartile range, 18-86) months. Time to treatment was subcategorized based on multivariate cubic spline cox model. In multivariate spline model, adjusted for all the pertinent pretreatment variables, inflection point in the risk of biochemical recurrence was observed around 3 months, which further increased after 6 months. Based on spline model, time to treatment was then divided into 0 to 3 months (61.5%), >3 to 6 months (31.1%), and 6 months (7.4%). In the adjusted cox model, initial delays up to 6 months did not adversely affect the outcome; however, time to treatment >6 months had significantly higher risk of biochemical recurrence (HR, 1.84; 95% confidence interval, 1.30-2.60; P < 0.01).

CONCLUSIONS

The initial delays up to 6 months in prostate cancer primary treatment may be sustainable without adversely affecting the outcome. However, significant delays beyond 6 months can unfavorably affect biochemical disease control.

IMPACT

Time to treatment can aid clinicians in the decision-making of prostate cancer treatment recommendation and educate patients against unintentional treatment delays.