Socioeconomic Barriers to Randomized Clinical Trial Retention in Patients Treated With Adjuvant Radiation for Early-Stage Breast Cancer

Purpose: Socioeconomic barriers contribute to breast cancer clinical trial enrollment disparities. We sought to identify whether socioeconomic disadvantage also is associated with decreased trial retention. Methods and Materials: We performed a secondary analysis of 253 (of 287) patients enrolled in a randomized phase 3 trial of conventionally fractionated versus hypofractionated whole-breast irradiation. The outcome of trial retention versus dropout was defined primarily based on whether the patient completed breast cosmesis outcomes assessment at 3-year follow-up, and secondarily, at 5-year follow-up. Associations of retention with severity of socioeconomic disadvantage, quantified by patients’ home neighborhood area deprivation index (ADI) rank (1 [least] to 100 [most deprivation]), were tested using the Kruskal-Wallis test and multivariate logistic regression. Associations of retention with patients’ use of social resource assistance were analyzed using the χ² test. Results: In total, 21.7% (n = 55) of patients dropped out by 3 years and 36.7% (n = 92) by 5 years. Median ADI was 36.5 (interquartile range, 22-57) for retained and 46.0 (interquartile range, 29-60) for dropout patients. Dropout was associated with more severe socioeconomic deprivation (ADI ≥45 vs <45) at 3 years (odds ratio, 3.63; 95% confidence interval, 1.62-8.15; P = .002) and 5 years (odds ratio, 2.55; 95% confidence interval, 1.37-4.76; P = .003). While on study, patients who ultimately dropped out were more likely to require resource assistance for practical (transportation, housing, financial) than psychological needs (distress, grief) or advance care planning (P = .03). Conclusions: In this study, ADI was associated with disparities in clinical trial retention of patients with breast cancer receiving adjuvant radiation treatment. Results suggest that developing multidimensional interventions that extend beyond routine social determinants needs screening are needed, not only to enhance initial clinical trial access and enrollment but also to enable robust long-term retention of socioeconomically disadvantaged patients and improve the validity and generalizability of reported long-term trial clinical and patient-reported outcomes.