Accrual of older adults to Canadian Cancer Trials Group (CCTG) led trials: A retrospective analysis from 1990 to 2015.

Abstract

10031 Background: Older adults (OA) age 65+ make up to 60% of all newly diagnosed cancers. However, only 22-32% of patients accrued in cooperative group studies in the 1990s were age 65+. In 2003, several studies suggested that clinical trial design, in particular the presence of strict exclusion criteria, was a major barrier to accrual of OA. The objective of this study was to determine: 1) whether there has been an improvement in accrual of OA to clinical trials led by the Canadian Cancer Trials Group (CCTG) over time; 2) clinical trial features associated with accrual of OA to clinical trials 3) whether exclusion criteria in trials initiated 2003 or after have been relaxed. Methods: All completed randomized Phase II and III CCTG-led clinical trials initiated between 1990 or later were included. Trial characteristics including tumor type, stage, treatment type, and exclusion/inclusion criteria, as well as percentage of OA age 65+ accrued were recorded. Association between percentage of OA accrued and trial characteristics were compared using the Wilcoxin rank sum test. Assessment of exclusion criteria before and after 2003 was compared using the Chi Square test or Fisher exact test. Results: A total of 68 trials were included. Most trials were phase III (73%), chemotherapy trials (48%), opened before 2003 (70.6%), advanced disease (73%) and lung cancer was the most common tumour site (17.6%). OA accrual remains low compared to OA diagnosed with cancer in Canada (41% vs. 56%, p < 0.001). There was an improvement in accrual of OA after 2003 (47.1% vs. 34.9%, p = 0.02). Tumour site, early stage disease, more restrictive performance status, requiring a new biopsy, and having a longer consent form, were associated with lower accrual of OA (p < 0.05). There was no significant loosening of exclusion with time though patients with pulmonary comorbidities were more likely to be excluded in studies initiated in 2003 or later (p = 0.006). Conclusions: OA remain under-represented in clinical trials. There has been no relaxing of exclusion criteria; however, exclusion based on comorbidities was not significantly associated with under accrual of OA in our study.