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

In this issue of Annals of Oncology, Halabi and colleagues present an interesting and important article that evaluates clinical outcomes in a diverse cohort of men with metastatic castration-resistant prostate cancer (mCRPC).1Halabi S. Dutta S. Tangen C.M. et al.Clinical outcomes in men of diverse ethnic backgrounds with metastatic castration-resistant prostate cancer.Ann Oncol. 2020; 31: 930-941Abstract Full Text Full Text PDF PubMed Scopus (5) Google Scholar In this study, the authors compared outcomes by race (white, black, and Asian) from individual patient data in 8820 men (including 500 black men) with mCRPC who were randomized on phase 3 clinical trials to docetaxel- (D) and prednisone- (P) based regimens. The study found no racial differences in median progression-free survival or biochemical events, defined by PSA progression. These study findings from high-level data inform historical trends in prostate cancer disparities. Namely, they provide evidence that men with similar disease characteristics who are treated similarly, as is the case in randomized trials, are unlikely to demonstrate racial disparities in prostate cancer outcomes. Similar findings have recently been published in men receiving radiation therapy or Sipuleucel-T therapy.2Dess R.T. Hartman H.E. Mahal B.A. et al.Association of black race with prostate cancer-specific and other-cause mortality.JAMA Oncol. 2019; 5: 975-983Crossref PubMed Scopus (106) Google Scholar,3Sartor O. Armstrong A. Ahaghotu C. McLeod D. Cooperberg M. Higano C. Overall survival of African-American and Caucasian men who received Sipuleucel-T for metastatic castration-resistant prostate cancer (mCRPC): final PROCEED analysis.J Clin Oncol. 2019; 37: 5035Crossref Google Scholar This growing body of evidence highlights the importance of access to high-quality equal care as a significant mitigator of prostate cancer disparities. However, unanswered questions remain. Overall, it should not be surprising that men with similar disease status and who receive similar treatment (on trial) have similar outcomes, regardless of race. Still, we must uncover and address why black men have a higher incidence of prostate cancer, and present with more aggressive disease that ultimately translates to higher mortality rates at the population level.4DeSantis C.E. Miller K.D. Goding Sauer A. Jemal A. Siegel R.L. Cancer statistics for African Americans, 2019.CA Cancer J Clin. 2019; 69: 211-233Crossref PubMed Scopus (237) Google Scholar,5Mahal B.A. Berman R.A. Taplin M.E. Huang F.W. Prostate cancer-specific mortality across Gleason scores in black vs nonblack men.JAMA. 2018; 320: 2479-2481Crossref PubMed Scopus (55) Google Scholar It is worth noting that the study findings are not discordant from population-level disparities in mortality rates—this has caused some recent confusion in the literature, thus the study findings should be contextualized in relation to population level estimates. In the United States, the incidence rate of prostate cancer is ∼180 in black men compared with ∼100 in white men, while the mortality rate is ∼40 in black men compared with ∼18 in white men (all per 100 000 persons). These are population-level estimates that describe the overall incidence and mortality of prostate cancer among all individuals in the population (with a denominator that includes men without prostate cancer).4DeSantis C.E. Miller K.D. Goding Sauer A. Jemal A. Siegel R.L. Cancer statistics for African Americans, 2019.CA Cancer J Clin. 2019; 69: 211-233Crossref PubMed Scopus (237) Google Scholar In contrast, the present study reports Kaplan–Meier measures among a cohort of individuals all diagnosed with mCRPC, and therefore the findings have little bearing on population-level estimates. For example, if one were to conclude that men with ‘equal’ disease characteristics who receive ‘equal’ treatment have ‘equal’ outcomes regardless of race, there would still be significant population-level disparities, driven by the excess incidence/burden of prostate cancer in black men. As a crude example, if we assume an equal 20% risk of dying from prostate cancer for black and white men (after diagnosis), then at the population level there would still be ∼36 black men that die for every ∼20 white men, which would translate to black men having a 1.8× higher population-level mortality rate (in an equal setting). As such, a significant proportion of prostate cancer disparities in population-level mortality is likely accounted for by the excess risk of black men developing prostate cancer. A concerted transdisciplinary effort will be needed to better uncover, understand, and address the drivers of prostate cancer disparities along the prostate cancer disease continuum to both speak to prostate cancer disparities and to better understand prostate cancer mechanisms of disease. None declared.