Background.A subgroup of adolescent and young adult (AYA) survivors of cancer during adolescence report high levels of psychological distress. To date, evidence-based psychological interventions tailored to the cancer-related concerns experienced by this population are lacking. The present study aimed to (1) examine the feasibility and preliminary efficacy of an individualized cognitive behavioral therapy (CBT) intervention for AYA survivors of cancer during adolescence; and (2) identify and conceptualize cancer-related concerns as well as maintaining factors using cognitivebehavioral theory. Methods. A single-arm trial, whereby AYA survivors of cancer during adolescence (aged 17-25 years) were provided individualized face-to-face CBT at a maximum of 15 sessions. Clinical outcomes were assessed at baseline, post-intervention, and three-month follow-up. Intervention uptake, retention, intervention delivery, and reliable change index scores were examined. An embedded qualitative study consisted of two unstructured interviews with each participant pre-intervention. Along with individual behavioral case formulations developed to guide the intervention, interview data was analyzed to identify and conceptualize cancer-related concerns and potential maintaining factors. Results. Ten out of 213 potential participants invited into the study were included, resulting in an overall participation rate of 4.7%. Nine participants completed the intervention, with respectively seven and eight participants completing the postintervention and three month follow-up assessment. The majority of reported cancerrelated concerns and maintaining factors were conceptualized into four themes: social avoidance, fear of emotions and bodily symptoms, imbalance in activity, and worry and rumination. Conclusions. Given significant recruitment difficulties, further research is required to examine barriers to help-seeking in the AYA cancer survivor population. However, the conceptualization of cancer-related concerns and maintaining factors experienced by the population may represent an important first step in the development of psychological support tailored toward AYA cancer survivors' unique needs. How to cite this article Hagström J, Ander M, Cernvall M, Ljótsson B, Wiman HW, von Essen L, Woodford J. 2020. Heeding the psychological concerns of young cancer survivors: a single-arm feasibility trial of CBT and a cognitive behavioral conceptualization of distress. PeerJ 8:e8714 http://doi.org/10.7717/peerj.8714 Ander M, Thorsell Cederberg J, Von Essen L, Hovén E. 2018. Exploration of psychological distress experienced by survivors of adolescent cancer reporting a need for psychological support. PLOS ONE 13(4):e0195899