Background:In-person cognitive-behavioral stress-management interventions are consistently associated with reduced cancer distress. However, face-to-face delivery is an access barrier for many patients, and there is a need to develop remote-delivered interventions. The current study evaluated the preliminary efficacy of an application (app)-based cancer stress-management intervention, StressProffen, in a randomized controlled trial. Methods: Cancer survivors, maximum 1-year posttreatment (N = 172), were randomized to StressProffen (n = 84) or a usual care control group (n = 88). Participants received a blended delivery care model: (a) one face-to-face introduction session, (b) 10 app-based cognitive-behavioral stress-management modules, and (c) followup phone calls at weeks 2-3 and 6-7. Outcome measures included stress (Perceived Stress Scale), anxiety and depression (Hospital Anxiety Depression Scale), and health-related quality of life (HRQoL; Short-Form Health Surveys [SF-36]) at 3-months post-intervention, analyzed with change scores as dependent variables in linear regression models. Results: Participants were primarily women (82%), aged 20-78 years (mean 52, SD 11.2), with mixed cancer types (majority breast cancer; 48%). Analysis of 149 participants completing questionnaires at baseline and 3 months revealed significant intervention effects: decreased stress (mean difference [MD] −2.8; 95% confidence interval [CI], [−5.2 to −0.4]; P = .022) and improved HRQoL (Role Physical MD = 17.7, [CI 3.7-31.3], P = .013; Social Functioning MD = 8.5, [CI 0.7-16.2], P = .034; Role Emotional MD = 19.5, [CI 3.7-35.2], P = .016; Mental Health MD = 6.7, [CI 1.7-11.6], P = .009). No significant changes were observed for anxiety or depression. Conclusions: Digital-based cancer stress-management interventions, such as StressProffen, have the potential to provide easily accessible, effective psychosocial support for cancer survivors. 3776 | BØRØSUND et al.