404P A quantitative synthesis of disparities in the inclusion of younger adults and racial/ethnic minorities in colorectal cancer clinical trials

Abstract

Colorectal cancer (CRC) incidence in younger adults has been rising for unclear reasons, and clinical outcomes also differ across racial/ethnic subpopulations. We analyzed all trials for age disparity and trials recruiting from the US for racial/ethnic disparity from primary reports of CRC randomized controlled trials (1990-2021). We calculated enrollment-incidence ratios (EIR), which compare trial enrollment from an age or racial/ethnic subgroup against global estimates of incidence in the corresponding age subgroup (from Global Burden of Disease) or US-population-based incidence in the corresponding racial/ethnic subgroup (from SEER 21). Individual-trial EIRs were pooled using random-effects meta-analyses. Meta-regression was used to explore associations between key trial characteristics and EIR, as well as trends in EIR over the last three decades. Of 411 global trials, 139 trials (33.8%) reported the number of patients within pre-defined age subgroups/categories; among these, patients were most frequently reported as above/below 65 years of age (n = 86; 20.9%). Only 12 trials (2.9%) reported the number of participants younger than 50 years, while even fewer reported the number of participants younger than 45 or 40 years (n = 8; 1.9%). 78 trials (19.0%) reported a subgroup analysis by age. Of 37 US trials, 19 trials (51.4%) reported race and 5 (13.5%) reported ethnicity, with only 2 (5.4 %) reporting data on all 5 U.S. racial categories. Patients aged >65 years were significantly underrepresented (EIR: 0.85 [95% CI: 0.78 - 0.94]). Asians were under-enrolled (EIR: 0.44 [95% CI: 0.36 - 0.52]), as well as Black (EIR: 0.57 [95% CI: 0.49 - 0.66]) and Hispanic patients (EIR: 0.51 [95% CI: 0.39 - 0.67]) with the inclusion of larger, international trials. There were no significant changes in the degree of disparity over the last three decades. Despite rising incidence of CRC in younger adults, clinical trials show infrequent reporting of this age group. Racial ethnic/minorities are significantly underrepresented in colorectal clinical trials based on their share of colorectal cancer incidence.