Missing diversity in brain tumor trials

Abstract

Background: Clinical trials for brain tumors represent a significant opportunity for both patients and providers to understand and combat a disease with substantial morbidity. The aim of this study was to quantify and map ethnic and racial representation in brain tumor trials and examine the potential gaps in trial recruitment. We also show that these representation gaps persist even in large multicultural cities like New York City.

Methods: We analyzed brain tumor clinical trials registered on www.clinicaltrials.gov between July 1, 2005 and completed on or before November 11, 2017. We used a combination of PubMed/MEDLINE and Google Scholar to find associated publications and obtained trial information as well as patient demographic information (when available) including race or ancestry.

Results: Out of 471 trials, 27% had no published results. Only 28.4% of trials with results reported race or ethnicity of trial participants, with no observed upward trend by year. Whites were significantly overrepresented in trials for metastatic brain tumors (P < .001) and high-grade trials (P < .001). Blacks/African Americans (AAs), Hispanics, and Asians were significantly underrepresented (P < .001) in high-grade trials, while only Blacks/AAs were underrepresented in trials for metastatic brain tumors (P < .001). Representation gaps were not observed in pediatric trials. Despite being a multicultural hub, New York City displayed similar gaps in trial representation.

Conclusions: Despite increasing representation in the American population, minorities are underrepresented in brain tumor trials. In addition, despite numerous legal requirements and ethical mandates, published results including race-based information are remarkably absent from 70% of brain tumor trials.

Keywords: representation; New York City; clinical trials; diversity; neuro-oncology.

Figure 1.

Reporting habits of trials historically sorted by start year of the trial, and that have been completed before November 11, 2017.

Figure 2.

Race reporting trends organized by intervention type.

Figure 3.

Race reporting habits for trials as a function of phase status.

Figure 4.

(Top left panel) Enrollment percentages over time for all racial groups analyzed for adult high-grade glioma trials. Single asterisk indicates statistically significant overrepresentation. Double asterisks indicate statistically significant underrepresentation. (Top right panel) Annual age-adjusted incidence rate converted into incidence proportions for all plotted groups, for GBM. Single asterisk indicates statistically significant overrepresentation. Double asterisks indicate statistically significant underrepresentation. (Middle left panel) Enrollment percentages over time for all racial groups analyzed for all metastatic brain tumor trials. (Middle right panel) Annual age-adjusted incidence rate for all plotted groups converted into incidence proportions, for all metastatic tumor types**. (Bottom left panel) Enrollment percentages over time for all racial groups analyzed for all pediatric brain tumor trials. (Bottom right panel) Enrollment percentages over time for all racial groups analyzed for all adult brain tumor trials. *Hispanic AAA IR for all brain tumor types taken from: Ostrom QT, Gittleman H, Xu J, et al. CBTRUS Statistical Report: Primary Brain and Other Central Nervous System Tumors Diagnosed in the United States in 2009–2013. Neuro Oncol. 2016;18(suppl_5):v1–v75. **Estimated from: Davis, Faith G, et al. Toward determining the lifetime occurrence of metastatic brain tumors estimated from 2007 United States cancer incidence data. Neuro-oncology 14.9(2012):1171–1177.

Figure 5.

(Top left panel; A) Enrollment percentages over time for all racial groups analyzed for brain tumor trials located within the 5 boroughs of New York City. (Top right panel; B) Density map of completed brain tumor trials for New York City. (Bottom left panel; C) The percentage of non-White minorities in each county within the 5 boroughs. (Bottom right panel; D) Per capita income distribution across the 5 boroughs.