Background: In oncology clinical trials, the assumption that a prior cancer diagnosis could interfere with study conduct or outcomes results in frequent exclusion of such patients. We determined the prevalence and characteristics of this practice in lung cancer clinical trials and estimated impact on trial accrual.
Methods: We reviewed lung cancer clinical trials sponsored or endorsed by the Eastern Oncology Cooperative Group for exclusion criteria related to a prior cancer diagnosis. We estimated prevalence of prior primary cancer diagnoses among lung cancer patients using Surveillance Epidemiology and End Results (SEER)-Medicare linked data. We assessed the association between trial characteristics and prior cancer exclusion using chi-square analysis. All statistical tests were two-sided.
Results: Fifty-one clinical trials (target enrollment 13072 patients) were included. Forty-one (80%) excluded patients with a prior cancer diagnosis as follows: any prior (14%), within five years (43%), within two or three years (7%), or active cancer (16%). In SEER-Medicare data (n = 210509), 56% of prior cancers were diagnosed within five years before the lung cancer diagnosis. Across trials, the estimated number and proportion of patients excluded because of prior cancer ranged from 0-207 and 0%-18%. Prior cancer was excluded in 94% of trials with survival primary endpoints and 73% of trials with nonsurvival primary endpoints (P = .06).
Conclusions: A substantial proportion of patients are reflexively excluded from lung cancer clinical trials because of prior cancer. This inclusion criterion is applied widely across studies, including more than two-thirds of trials with nonsurvival endpoints. More research is needed to understand the basis and ramifications of this exclusion policy.
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