Disparities in Clinical Trial Enrollment and Reporting in Rectal Cancer: A Systematic Review and Demographic Comparison to the National Cancer Database

Background: Cancer care guidelines based on clinical trial data in homogenous populations may not be applicable to all rectal cancer patients. The aim of this study was to evaluate whether patients enrolled in rectal cancer clinical trials (CTs) are representative of United States (U.S.) rectal cancer patients. Methods: Prospective rectal cancer CTs from 2010 to 2019 in the United States were systematically reviewed. In trials with multiple arms reporting separate demographic variables, each arm was considered a separate CT group in the analysis. Demographic variables considered in the analysis were age, sex, race/ethnicity, facility location throughout the United States, rural vs urban geography, and facility type. Participant demographics from trial and the National Cancer Database (NCDB) participants were compared using chi-squared goodness of fit and one-sample t-test where applicable. Results: Of 50 CT groups identified, 42 (82%) studies reported mean or median age. Trial participants were younger compared to NCDB patients (P <.001 all studies). All but three trials had fewer female patients than NCDB (48.2% female, P <.001). Less than half the CT groups reported on race or ethnicity. Eighteen out of 22 trials (82%) had a smaller percentage of Black patients and 4 out of 8 (50%) trials had fewer Hispanic or Spanish origin patients than the NCDB. No CTs reported comorbidities, socioeconomic factors, or education. CT primary sites were largely at academic centers and in urban areas. Conclusion: The present study supports the need for improved demographic representation and transparency in rectal cancer clinical trials.