Racial Disparities in Clinical Trial Participation: Evidence from Real World Oncology Data

Background: Black patients are underrepresented in cancer clinical trials, limiting the generalizability of trial results and contributing to disparities in access to novel therapies.

Objectives: Here we examine racial disparities in oncology trial participation from 2017 to 2021.

Methods: This retrospective study uses data from the de-identified, electronic health record (EHR)-derived Flatiron Health database from the US. The cohort included patients diagnosed with five common cancers between January 2017 and September 2021 (follow-up through December 2021) and initiated treatment. We examined differences between Black and White patients in trial participation (defined as documented receipt of clinical trial drugs after diagnosis). To characterize differences in trial participation, we used a time-to-event analysis where patients were followed from diagnosis to their first treatment with a clinical trial drug, death, or last recorded activity. Cox proportional hazards model adjusted for demographic characteristics (age, sex, and diagnosis year) were used to calculate hazard ratios (HR) and 95% confidence intervals (CI).

Results: The cohort included 45,750 patients (15% Black, 56% female, median age of 68, 87% from community oncology practices). During the study period, 5.2% of patients participated in clinical trials, including 3.5% of Black patients and 5.4% of White patients. Black patients were less likely to participate in trials than White patients (HR 0.61 [CI: 0.54-0.70]). This disparity varied by disease (advanced non-small cell lung cancer: HR 0.48 [CI: 0.37-0.62]; pancreatic cancer: HR 0.47 [CI: 0.31-0.72]; metastatic breast cancer: HR 0.65 [CI: 0.47-0.88]; multiple myeloma: HR 0.65 [CI: 0.44-0.94]; metastatic colorectal cancer: HR 0.88 [CI: 0.68-1.13]). The magnitude of overall Black-White differences in trial participation increased between patients diagnosed in 2017 (HR 0.79 [CI: 0.63-1.00]) and 2021 (HR 0.51 [CI: 0.31-0.83]).

Conclusions: Black patients are approximately 35% less likely to participate in oncology clinical trials, a disparity that has persisted in the last five years and has worsened by 2021—in the midst of the COVID-19 pandemic. Policy efforts to increase Black patient enrollment in clinical trials should include target accrual rates of racial and ethnic minority patients in trials.