Disparities in clinical trial enrollment at a Canadian comprehensive cancer center: A 15-year retrospective study

Gilla K Shapiro; Anna T Santiago; Tyler Pittman; Kai Iwano; Gary Rodin; Heather Cole; Katherine Zeman; Susanna Sellmann; Amit M Oza; Jennifer Jones; Meredith Rosenthal; Rena M Conti; Danielle Rodin

doi:10.1002/cncr.35331

Disparities in clinical trial enrollment at a Canadian comprehensive cancer center: A 15-year retrospective study

Cancer. 2024 Apr 25. doi: 10.1002/cncr.35331. Online ahead of print.

Authors

Gilla K Shapiro^{1

2}, Anna T Santiago³, Tyler Pittman^{3

4}, Kai Iwano⁵, Gary Rodin^{1

2}, Heather Cole⁶, Katherine Zeman⁶, Susanna Sellmann⁶, Amit M Oza^{7

8}, Jennifer Jones^{1

2}, Meredith Rosenthal⁹, Rena M Conti¹⁰, Danielle Rodin^{5

11}

Affiliations

¹ Department of Supportive Care, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada.
² Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada.
³ Department of Biostatistics, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada.
⁴ Department of Community Health and Epidemiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
⁵ Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada.
⁶ Cancer Clinical Research Unit, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada.
⁷ Division of Medical Oncology and Haematology, Princess Margaret Cancer Centre, Toronto, Ontario, Canada.
⁸ Department of Medicine, University of Toronto, Toronto, Ontario, Canada.
⁹ Department of Health Policy and Management, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, USA.
¹⁰ Department of Markets, Public Policy, and Law, Boston University Questrom School of Business, Boston, Massachusetts, USA.
¹¹ Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada.

PMID: 38662430
DOI: 10.1002/cncr.35331

Abstract

Introduction: Disparities in clinical trials (CTs) enrollment perpetuate inequities in treatment access and outcomes, but there is a paucity of Canadian data. The objective of this study was to examine disparities in cancer CT enrollment at a large Canadian comprehensive cancer center.

Methods: Retrospective study of CT enrollment among new patient consultations from 2006 to 2019, with follow-up to 2021 (N = 154,880), with the primary outcome of enrollment as a binary variable. Factors associated with CT enrollment were evaluated using multivariable Bayesian hierarchical logistic regression with random effects for most responsible physician (MRP) and geography, adjusted for patient characteristics (sex, age, language, geography, and primary care provider [PCP]), area-level marginalization (residential instability, material deprivation, dependency, and ethnic concentration), disease (cancer site and stage), and MRP (department, sex, language, and training). A sensitivity analysis of the cumulative incidence of enrollment was conducted to account for differences in disease type and follow-up length.

Results: CT enrollment was 11.2% overall, with a 15-year cumulative incidence of 18%. Lower odds of enrollment were observed in patients who were female (adjusted odds ratio [AOR], 0.82; 95% confidence interval [CI], 0.78-0.86), ≥65 years (AOR vs. <40, 0.61; 95% CI, 0.56-0.66), non-English speakers (0.72; 95% CI, 0.67-0.77), living ≥250 km away (AOR vs. <15 km, 0.71; 95% CI, 0.62-0.80), and without a PCP. Disease characteristics accounted for the largest proportion of observed variation (20.8%), with significantly greater odds of enrollment in patients with genitourinary cancers and late-stage disease.

Conclusion: Significant sociodemographic disparities were observed, suggesting the need for targeted strategies to increase diversity in access to cancer CTs in Canada.

Keywords: cancer; clinical trials; disparities; health equity; minority participation.

Grants and funding

Princess Margaret Cancer Foundation