LAUSR

Importance Clinical trials play a critical role in the development of novel cancer therapies, and precise estimates of the frequency with which older adult patients with cancer participate in clinical trials are lacking. Objective To estimate the proportion of older adult Medicare Fee-for-Service (FFS) beneficiaries with cancer who participate in interventional cancer clinical trials, using a novel population-based methodology. Design, Setting, and Participants In this retrospective cohort study evaluating clinical trial participation among older adult patients with cancer from January 1, 2014, through June 30, 2020, claims data from Medicare FFS were linked with the ClinicalTrials.gov to determine trial participation through the unique National Clinical Trial (NCT) identifier. The proportion of patients with newly diagnosed or newly recurrent cancer in 2015 participating in an interventional clinical trial and receiving active cancer treatment from January 2014 to June 2020 was estimated. Data analysis was performed from November 18, 2020, to November 1, 2021. Exposures Patients with cancer aged 65 years or older with Medicare FFS insurance, with and without active cancer treatment. Main Outcomes and Measures Enrollment in clinical trials among all patients with cancer 65 years and older and among patients receiving active cancer treatments as defined by the presence of at least 1 NCT identifier corresponding to an interventional cancer clinical trial in Medicare claims. Results Among 1 150 978 patients (mean [SD] age, 75.7 [8.4] years; 49.9% men and 50.1% women) with newly diagnosed or newly recurrent cancer in 2015, 12 028 (1.0%) patients had a billing claim with an NCT identifier indicating enrollment in an interventional cancer clinical trial between January 2014 and June 2020. In a subset of 429 343 patients with active cancer treatment, 8360 (1.9%) were enrolled in 1 or more interventional trials. Patients enrolled in a trial tended to be younger, male, a race other than Black, and residing in zip codes with high median incomes. Conclusions and Relevance Findings of this cohort study show that clinical trial enrollment among older adult patients with cancer remains low, with only 1.0% to 1.9% of patients with newly diagnosed or recurrent cancer in 2015 participating in an interventional cancer clinical trial as measured by the presence of NCT identifiers in Medicare claims. These data provide a contemporary estimate of trial enrollment, persistent disparities in trial participation, and only limited progress in trial access over the past 2 decades.