How representative are participants in geriatric oncology clinical trials? The case of the 5C RCT in geriatric oncology: A cross-sectional comparison to a geriatric oncology clinic.

Introduction: Frail older adults make up a substantial portion of the older adult population. However, frail patients are often excluded from randomized controlled trials. This underrepresentation restricts the extent to which trial findings can be generalized to this population. We compared a sample from the Canadian 5C Randomized Controlled Trial investigating comprehensive geriatric assessment (CGA) in the geriatric oncology setting in terms of frailty to patients referred to the Older Adults with Cancer Clinic (OACC) to determine if the trial sample was representative of the normal geriatric oncology practice.

Materials And Methods: Baseline CGA data of 5C Trial participants seen at the Princess Margaret Cancer Centre (PM), were compared to data from OACC patients that were seen during the duration of the 5C trial (between April 2018 and April 2020) and that satisfied the 5C inclusion criteria. To assess the frailty of samples, sex, age, disease site, comorbidity level, medical optimization, social supports, functional status, falls risk, nutrition, cognition, and mood were compared between 5C participants and OACC patients using Fisher's exact and independent samples t-test.

Results: A sample of 115 5C participants and 205 OACC patients were included. The mean age of 5C participants and OACC patients was 75.4 and 81.6 years, respectively (p < 0.001). The distribution of disease sites was significantly different between the samples (p < 0.001) and OACC patients were also significantly more impaired compared to 5C participants in comorbidity (23.4% versus 10.4% high comorbidity) (p = 0.001), IADL dependence (55.1% versus 42.6%) (p = 0.036), impaired physical function (70.6% versus 31.3%) (p < 0.001), falls risk (67.8% versus 27%) (p < 0.001), impaired nutrition (55.6% versus 40.9%) (p = 0.014), and cognition (47.2% versus 10%) (p < 0.001). There were no differences in sex, medication optimization, poor social supports, and impaired mood between the samples.

Discussion: The 5C sample was less frail and younger than patients seen in the geriatric oncology clinic. Finding strategies to address barriers to the inclusion of frailer older adults is important to increase their representation in future trials to allow findings to be generalized to this vulnerable population.

Trial Registration: Clinicaltrials.gov # NCT03154671.