In a study reported in the Journal of Clinical Oncology, Owens-Walton et al found that minority populations are underrepresented in phase II and III trials targeting prostate, kidney, and bladder cancers taking place in the United States.

Study Details

In the analysis, the ClinicalTrials.gov registry was searched for U.S. phase II and III interventional trials in bladder/urothelial, kidney, and prostate cancers completed between January 2000 and December 2017. The SEER database from 2000 to 2017 was used to calculate the U.S. prevalence of these cancers. Representation quotients were calculated to indicate the relative proportion of each racial/ethnic group enrolled in clinical trials over the proportion of persons from each group among national cancer cases by cancer type.

Key Findings

Among 341 trials meeting initial eligibility criteria, 169 (49.7%) reported data on race or ethnicity. Of these, 152 were phase II and 17 were phase III trials.  

Aggregate representation quotients over the entire study period showed that White patients were over-represented for each cancer type: bladder = 1.10, kidney = 1.23, and prostate = 1.15. Black patients were under-represented for each cancer type: bladder = 0.51, kidney = 0.59, and prostate = 0.72. Asians/Pacific Islanders were under-represented in kidney and prostate cancers: bladder = 0.94, kidney = 0.80, and prostate = 0.63. When stratified by 3-year increments, representation quotients remained stable for all races between 2000 to 2017. By ethnicity, aggregate representation quotients for Hispanic patients were 0.80 for bladder, 0.49 for kidney, and 0.75 for prostate cancers.

Among 80 trials funded by the U.S. government, representation quotients for bladder, kidney, and prostate cancers were: 1.10, 1.21, and 1.08 among White patients; 0.47, 0.84, and 1.04 among Black patients; and 0.78, 0.41, and 0.64 among Asian/Pacific Islander patients.

Among 60 trials funded by industry sponsors, representation quotients for bladder, kidney, and prostate cancers were: 1.06, 1.19, and 1.18 among White patients; 0.74, 0.69, and 0.60 among Black patients; and 1.56, 1.11, and 0.66 among Asian/Pacific Islander patients.

The investigators concluded, “Clinical trials targeting prostate, kidney, and bladder cancers continue to under-represent racial/ethnic minority patients. On the basis of the incidence of these cancers within minority populations, efforts should focus on creating racially and ethnically inclusive cancer research.”

Mark W. Ball, MD, of the Urologic Oncology Branch, National Cancer Institute, National Institutes of Health, is the corresponding author for the Journal of Clinical Oncology article.

Disclosure: The study was supported by the NIH Intramural Program and others. For full disclosures of the study authors, visit ascopubs.org.