Drawing on the presentation from Dr. Yamoah, he highlighted that while we currently observe significant differences in prostate cancer outcomes between Black and White men, we would expect equivalent outcomes if there was an equivalent and timely diagnosis, adequate staging, and risk stratification, and equitable treatment delivery. Each of the highlighted abstracts addresses one of these issues.
First, Dr. Black considered the work presented by Dr. Qiao regarding prostate-specific antigen screening among young African American men in the Veterans Affairs system. He noted that, while trials have demonstrated the benefit of prostate cancer screening, African American men are vastly under-represented in these clinical trials. Among younger African American men diagnosed with prostate cancer the authors found that the intensity of PSA screening prior to diagnosis was associated with disease severity at diagnosis, as measured by high-risk characteristics including high-grade histology, PSA ≥ 20 ng/mL, and metastatic disease. In addition, the authors found lower prostate cancer-specific mortality among men with a higher intensity of PSA screening in the pre-diagnostic period.
Dr. Black highlighted that we already have evidence that PSA screening reduces prostate cancer-specific mortality in White men on the basis of data from the ERSPC trial. However, African American men have a greater burden of disease, manifest with younger age at diagnosis and higher incidence of disease. Additionally, African American men have lower access to PSA screening. However, this present study demonstrates potential benefits from the use of PSA screening in a younger, African American population. He emphasized that there are limitations to this analysis including its retrospective design, reliance only on men who are diagnosed with prostate cancer, unvalidated use of lead-time adjustment, and questions regarding the generalizability of data from the VA system. However, we are unlikely to have prospective trial data to address this question. Further, PSA screening is likely to have an even greater effect on prostate cancer-specific mortality in African American men. Thus, this encourages a screening policy starting at age 40 years in African American men as NCCN recommends.
Moving to the second abstract, Dr. Black emphasized that while the Genomic Classifier has been well assessed in the literature and have proven prognostic ability for adverse pathology, biochemical recurrence, metastasis-free survival, and prostate cancer-specific mortality, African American men are poorly represented in the cohorts in which these tests have been derived and validated. Thus, the performance of African American men is uncertain.
He highlighted that multiple retrospective studies have demonstrated no difference in the prognostic ability of a number of different genomic tests in prostate cancer as a result of patient race.
Indeed, prior work assessing the Decipher Genomic Classifier found very comparable performance of the GC to predict metastasis and prostate cancer-specific mortality for African American and non-African American men following radical prostatectomy in an equal access health care system. The present study represents a prospective validation of the genomic classifier.
Importantly, Dr. Black highlighted that the authors showed that African American men are more likely to be reclassified to high genomic risk, within each stratum of risk defined based on NCCN criteria of clinicopathologic characteristics.
Based on this race-matched analysis, Dr. Black concluded that the genomic classifier outperforms risk stratification using clinical data in African American men. Further, it performs at least as well in African American men as in non-African American men. Thus, it should be used independently of race.
Finally, Dr. Black considered the presentation from Dr. Mahal, examining the association between genomic ancestry as defined based on SNP profiling and commercial sequencing of advanced prostate cancer.
Importantly, in the clinically annotated data, men of African ancestry who underwent comprehensive genomic profiling were less likely to be treated at academic centers, more likely to have under multiple lines of therapy prior to testing, and less likely to be offered therapy on a clinical trial.
In the thousands of men who underwent comprehensive genomic profiling, Dr. Black highlighted that there are a number of differential genomic alterations that are not explained by prior treatment. However, the lack of clinical annotation in this dataset limits conclusions.
Dr. Black concluded that the work presented by Dr. Mahal should that genetic alterations are found at similar rates between men of African and European ancestry. Thus, observed disparities in outcomes for men with prostate cancer are largely independent of differences in intrinsic tumor biology. Thus, disparities in health care delivery, including later utilization of genetic testing and less enrollment in clinical trials, likely contribute to the observed differences in outcomes.
In conclusion, Dr. Black emphasized the importance of moving from identifying disparities in outcomes to the implementation of changes to achieve equity.
Presented by: Peter Black, MD, Senior Research Scientist, Vancouver Prostate Centre, Associate Director, Clinical Research, Vancouver Prostate Centre, Professor, Department of Urologic Sciences, University of British Columbia
Written by: Christopher J.D. Wallis, Urologic Oncology Fellow, Vanderbilt University Medical Center Contact: @WallisCJD on Twitter at the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting, Virtual Annual Meeting #ASCO21, June, 4-8, 2021