Consent to Future Use of Residual and Banked Specimens Among Adults with Hematologic Malignancies: Analyzing SWOG Clinical Trial Data from 2000-2024

Introduction: Racial and socioeconomic disparities have been shown to influence long-term outcomes among adults with hematologic malignancies. Equitable research participation in clinical trials is essential to understand and alleviate such disparities. To this end, regulatory efforts by the National Institutes of Health have aimed, and continue to aim, to increase diversity of enrollees in clinical trials and secondary analyses. Prior studies outside of hematology have demonstrated differences in consent rates for biospecimen storage and secondary analysis among various sociodemographic groups. To inform our understanding of possible racial and socioeconomic disparities among adults with hematologic malignancies participating in U.S. cooperative group clinical trials, we analyzed rates of consent to future use of residual and banked specimens for all SWOG clinical trial participants from 2000-2024.

Methods: We identified 3,597 adults with a hematologic malignancy (AML, APL, ALL, CLL, CML, MDS) participating in a SWOG clinical trial between 2000-2024, including 3,100 with data on race and ethnicity available; the latter formed the cohort for this analysis. Collected data include consent to future use of residual and banked specimens, demographic information (i.e., age, sex, self-identified race and ethnicity), diagnosis, disease classification (i.e., newly diagnosed, relapsed or refractory), trial design (i.e., single-arm or randomized), year of registration (i.e., 2000-2010, 2011-2016, 2017-2024), and SWOG study. Sub-group analyses and Kaplan-Meier curves were utilized to analyze differences over time.

Results: Among 3,597 adult participants of SWOG clinical trial we identified in our retrospective analysis, 3,101 (86%) consented to future specimen use. Most clinical trial participants were male (n=2,068, 57%), Caucasian/White (n=3,019, 84%), and non-Hispanic (n=2,901, 81%). Several variables were significantly associated with consenting to future specimen use: race (p<0.001), ethnicity (p=0.0025), malignancy type (p<0.001), relapsed or refractory disease (p=0.045), single-arm trial design (p<0.001), and year of registration (p<0.001). Rates of consent were lowest for Hawaiian/Pacific Islanders (n=8, 53%) and Asians (n=69, 68%) and highest for Caucasian/Whites (n=2,601, 86%) and African American (n=188, 93%). Participants with MDS and CML were least likely to consent (n=245, 71%; n=378, 78%, respectively), while those with AML (n =1,942, 89%), ALL (n=278, 91%) and APL (n=173, 97%) were more likely. Significant inter-study consent variations were identified (range 50%-100%; median 92%). Cross-study consent by time period ranged from 79% (2017-2024) to 90% (2011-2016). In contrast, no significant differences in overall survival were found among those who consented to future specimen use.

Conclusion: In this multi-center analysis of SWOG clinical trial participants, we found significant disparities in consent for future specimen use by self-identified race/ethnicity, malignancy, disease classification, trial design, and time frame. Potential explanations for racial/ethnic disparities include structural racism, various historical and modern healthcare inequities fostering research distrust, and sociolinguistic barriers, whereas differences in disease severity may explain differences among malignancy, disease classification, and trial design. While national regulatory efforts to increase diversity may have contributed to increased consent rates for future specimen use and future contact, further ethnographic research is needed to understand patient decision-making processes; such efforts may improve hematological outcomes long-term and increase fidelity in clinical research.

Funding: NIH/NCI grants U10CA180888, U10CA180819