Understanding factors associated with breast cancer clinical trial participation.
Authors: Caston Nicole E. , Deng Luqin , Levitan Emily , Azuero Andres , Griffin Russell , Smith Karen L. , Gallagher Kathleen D. , Angove Rebekah SM , Williams Courtney , Wheeler Stephanie B. , Rocque Gabrielle Betty 
Published: October 2023

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Background: Although cancer clinical trials offer novel treatments which advance cancer care, participating patients do not represent real-world populations. It is unclear how patient sociodemographics, attitudes, and knowledge about clinical trials may influence patient’s participation in breast cancer (BC) clinical trials. Methods: This cross-sectional analysis used survey data collected in December 2022 by Patient Advocate Foundation (PAF), a nationwide non-profit organization providing social needs navigation and financial assistance to individuals with a chronic illness. Women diagnosed with early stage BC within the last five years or metastatic BC at any time and who received PAF services were included. Respondents reported participation in a BC clinical trial, attitudes towards (Attitudes Toward Cancer Trials Scale; scored 18-126, higher scores indicate more positive attitudes), and knowledge about cancer clinical trials (scores 0-7, higher scores indicate more knowledge about clinical trials). Patient-reported sociodemographic and clinical data included age at diagnosis, race (White, Black, Indigenous, or a Person of Color [BIPOC]), education level (high school or lower, some college, Bachelor’s or higher), annual household income (< or ≥ $50,000), employment status (employed, unemployed/other, retired/disabled), BC stage (early, late). Descriptive and bivariate analyses were conducted using Cramer’s V or Cohen’s d as effect sizes. A hypothesized path model was evaluated with a Structural Equation Model (SEM). Estimated standardized direct, indirect, and total effects of variables of interest on clinical trial participation were evaluated with 0.1, 0.3, and 0.5 indicating weak, medium, and large magnitude, respectively. Results: All 358 respondents were eligible to be included in our analysis. Overall, 39% were BIPOC, 38% had a Bachelor’s degree or higher, 69% had incomes <$50,000, and 49% were retired or disabled. Respondent clinical trial knowledge was low (mean 3.5, standard deviation (SD) 1.9). Respondents who reported trial participation (15%, n=54) more often had a Bachelor’s degree or higher (50% vs 36%; V 0.12) and more positive attitudes toward trials (mean 88, SD 23.3 vs 83, SD 15.6; d 0.29) compared to those not reporting participation. SEM (RMSEA=.02) revealed that positive attitudes towards, but not knowledge of, cancer clinical trials were associated with prior clinical trial participation (standardized total effect 0.13, p=0.01; 0.04, p=0.47, respectively). Knowledge of clinical trials was associated with positive attitudes toward clinical trials (0.15, p=0.003). No other sociodemographic variable had a statistically significant association with BC clinical trial participation. Conclusions: Future interventions to increase enrollment should focus on promotion of positive attitudes towards clinical trials, potentially through increased trial knowledge.