A Case-Control Study Examining Disparities in Clinical Trial Participation Among Breast Surgical Oncology Patients

Clinical trial participation among racial and ethnic minorities remains low despite national efforts. We sought to determine how participation in clinical trials by breast surgical oncology patients has changed over time and what characteristics are associated with participation.

Women with breast cancer enrolled in National Cancer Institute-sponsored, cooperative-group trials from 2000 to 2012 and who underwent oncologic surgery (n = 17 125) were compared with trial-eligible women in the National Cancer Database diagnosed in 2000-2012 (n = 792 719). Race-specific trial participation was plotted over time by income and reported as a proportion of the combined cohorts. Factors associated with trial participation were estimated using logistic regression; we report odds ratios (ORs) with 95% confidence intervals (CIs). A P value less than  .05 was considered statistically significant for all analyses. All tests were two-sided.

Participation declined across all groups over time because of a decrease in the scale and number of trials. In 2000-2003, Asian-Pacific Islander (7.17%), Hispanic (3.48%), and white (7.13%) patients from the highest income group had higher participation than their lower-income counterparts (Asian-Pacific Islander: 3.95%; Hispanic: 2.67%; white: 5.96%), but by 2008-2012, only high-income white patients participated more than lower-income whites (0.32% vs 0.25%, all P < .01). Black (OR = 0.80, 95% CI = 0.75 to 0.85) and Hispanic (OR = 0.84, 95% CI = 0.77 to 0.92) patients were less likely to participate than whites, but there were statistically significant interactions between income and race and ethnicity, with high-income black patients being approximately 50% less likely to participate than lower-income blacks (all P < .001).

Multifaceted interventions addressing the intersectionality of race, ethnicity, and other patient characteristics are needed to address persistent disparities in trial participation among breast surgical oncology patients.