Unveiling Factors Associated With Older Adult Accrual to Cancer Clinical Trials: Lessons From the ECOG-ACRIN...

Older adults (OAs) constitute ≥50% of patients with cancer in the United States yet are underrepresented in clinical trials. This study aimed to evaluate the representation of OAs in ECOG-ACRIN (EA) clinical trials and identify factors associated with their participation.

OA representation was evaluated in landmark EA trials completed between 2005 and 2019 across breast, gastrointestinal, genitourinary, hematologic, and thoracic malignancies. Enrollment was analyzed by age group and compared with age distributions from population-based SEER registries. Each protocol's eligibility criteria were reviewed for restrictions, such as any history of atrial fibrillation, New York Heart Association Class I-II heart failure, any cancer within 5 years, serum creatinine level exceeding the institutional upper limit of normal, creatinine clearance (CrCl) <50 mL/min, abnormal thyroid-stimulating hormone level, or chronic obstructive pulmonary disease on treatment. Chi-square tests were used to compare OA enrollment by race, ECOG performance status (PS), and community versus academic sites.

A total of 15 trials with 26,735 participants were included. The median age at enrollment was 58 years (range, 18-92), with 26% of participants aged ≥65 years. Across all tumor types, the median enrollment age was lower than the SEER median age at diagnosis, most notably in genitourinary malignancies (59 vs 73 years). Exclusion criteria were nonrestrictive in only 33% of trials; those with restrictive criteria enrolled participants of lower median age (57 vs 65 years; P<.001). The proportion of Black/African American participants declined with increasing age (<65 years: 9.6%; 65-75 years: 6.4%; >75 years: 4.8%; P<.0001). Although older adult enrollment was statistically higher at community compared with academic sites, absolute rates remained low (65-75 years: 23.7% vs 20.8%; >75 years: 5.6% vs 4.0%; P=.036).

OAs, particularly those from racial and ethnic minority groups, remain underrepresented in EA trials across all cancer types, with restrictive eligibility criteria contributing to their underenrollment. Continued efforts are needed to reduce barriers to the enrollment of older adults in clinical trials to ensure representation that reflects the age-related diversity of the cancer population.