AbstractBackgroundThe Early CDT®-Lung antibody blood test plus serial computed tomography scans for test-positives (TPGs) reduces late-stage lung cancer presentation. This study assessed the psychological outcomes of this approach.MethodsRandomized controlled trial (n= 12 208) comparing psychological outcomes 1–12 months post-recruitment in a subsample (n= 1032) of TPG, test-negative (TNG) and control groups (CG).ResultsCompared to TNG, TPG had lower positive affect (difference between means (DBM), 3 months (3m: −1.49 (−2.65, − 0.33)), greater impact of worries (DBM 1m: 0.26 (0.05, 0.47); 3m: 0.28 (0.07, 0.50)), screening distress (DBM 1m: 3.59 (2.28, 4.90); 3m: 2.29 (0.97, 3.61); 6m: 1.94 (0.61, 3.27)), worry about tests (odds ratio (OR) 1m: 5.79 (2.66, 12.63) and more frequent lung cancer worry (OR 1m: 2.52 (1.31, 4.83); 3m: 2.43 (1.26, 4.68); 6m: 2.87 (1.48, 5.60)). Compared to CG, TPG had greater worry about tests (OR 1m: 3.40 (1.69, 6.84)). TNG had lower negative affect (log-transformed DBM 3m: −0.08 (−0.13, −0.02)), higher positive affect (DBM 1m: 1.52 (0.43, 2.61); 3m: 1.43 (0.33, 2.53); 6m: 1.27 (0.17, 2.37)), less impact of worries (DBM 3m: −0.27 (−0.48, −0.07)) and less-frequent lung cancer worry (OR 3m: 0.49 (0.26, 0.92)).ConclusionsNegative psychological effects in TPG and positive effects in TNG were short-lived and most differences were small.