Effects of Mobile Application‐Based Cognitive Behavioral Therapy on Psychological Outcomes in Women Treated for Breast Cancer: A Randomized Controlled Pilot Trial in Germany

ABSTRACT Objective Breast cancer has a strong impact on the mental state of those affected. Cognitive behavioral therapy (CBT) is one effective approach to reduce disease burden. This randomized controlled pilot trial aimed to assess the effect of the digital CBT‐based application Living Well on psychological outcomes in a German female breast cancer population. Methods Female breast cancer patients ( n = 70) with ongoing or finished oncological treatment that is who were receiving or had received any type of oncological treatment were included in the study and randomized to an intervention group (IG, n = 32) receiving Living Well in addition to care as usual, and a control group (CG, n = 38) receiving care as usual only. Participants completed standardized questionnaires at baseline and after 2, 4, 8, and 12 weeks to assess anxiety and depression (HADS) as primary outcomes, distress (DT), health‐related quality of life (HRQoL, AQoL‐8D), and illness perception (B‐IPQ) as secondary outcomes. Results After 12 weeks, significant ( p < 0.05) higher improvements in the IG could be observed in anxiety levels, HRQoL, and illness perception, when compared to the CG. Age and time since diagnosis were found to be relevant covariates for anxiety levels. In distress levels, the IG showed a clinically relevant and nearly significant reduction compared to the CG ( p = 0.057). No effects could be observed in depression levels. Conclusions The results demonstrate the potential of Living Well to improve psychological outcomes of female breast cancer patients and encourage further studies evaluating the effectiveness of the digital application. Trial Registration: The trial has been registered in the German Clinical Trials Register (DRKS00029918)