This study will develop and evaluate a mobile-based co-design intervention (CesiKids) to enhance psychosocial resilience in hospitalized adolescents aged 12-18 diagnosed with cancer. The program will be created using Bronfenbrenner's Ecological Systems Theory and designed in collaboration with nurses, recovered adolescents, and parents. A randomized controlled design will be used. The intervention group will participate in a four-week structured program, while the control group will receive standard care. Psychosocial resilience and coping outcomes will be assessed at baseline, post-intervention, and follow-up. This research aims to offer an evidence-based, scalable model to support resilience among adolescents with cancer in clinical settings.

This study aims to develop an innovative mobile-based co-design intervention program to strengthen psychosocial resilience among adolescents aged 12-18 diagnosed with cancer. The program will be structured based on Bronfenbrenner's Ecological Systems Theory, addressing adolescents' individual characteristics, family and close-social environment, and broader ecological interactions in a holistic manner. To date, no study has implemented a theoretically grounded, mobile psychosocial intervention designed specifically to enhance resilience in adolescents with cancer through a co-design process involving nurses, recovered adolescents, and parents. This project aims to fill this gap by presenting a model that can be integrated into both clinical practice and educational settings.

The research will be conducted using a randomized controlled experimental design with intervention and control groups. The intervention group will participate in the newly developed mobile CesiKids program and engage in structured sessions for four weeks to enhance psychosocial resilience skills. The control group will receive standard clinical care. Participants' coping and psychosocial resilience levels will be measured using the Pediatric Cancer Coping Scale (PCCS) and the Child and Youth Resilience Measure (CYRM-R). Data collection will take place at baseline (T0), post-intervention (T1) and during follow-up assessments (T2 and T3). Quantitative data will be analyzed statistically, and the feasibility and usability of the program will also be monitored.

The CesiKids application will be developed by the project leader and research team. Data collection will be carried out by a nurse researcher experienced in pediatric oncology. All intervention, data collection, and analysis procedures will be carefully planned and monitored. All study data will be anonymized and accessible only to the research team. Data will be securely stored on protected servers and maintained throughout the project. All research processes will be conducted in accordance with ethical standards, and participant rights will be fully respected.

The project is expected to generate an evidence-based model that enhances psychosocial resilience among adolescents with cancer. The developed program will be applicable and scalable in both clinical and educational environments. Findings will be disseminated through academic publications, conference presentations, and among relevant healthcare institutions to ensure sustainability and maximize societal impact. Ultimately, this study intends to provide a practical contribution to the field of adolescent psychosocial resilience and to support the adaptation of similar interventions for other chronic illness groups.

Inclusion Criteria:

• Parents have provided informed consent after receiving information,
• The child has given assent to participate after being informed,
• The child is between 12 and 18 years of age,
• The child has been diagnosed with cancer and is currently receiving inpatient treatment,
• The child is undergoing chemotherapy and/or radiotherapy,
• The child is able to use a computer and/or smartphone,
• The child can understand and speak Turkish.

Exclusion Criteria:

• Receiving hematopoietic stem cell transplantation treatment,
• Having developed a relapse after remission,
• Experiencing communication difficulties (e.g., intellectual disability, visual impairment, etc.),
• Having a psychiatric diagnosis made by a psychiatrist,
• Having experienced a significant life event affecting psychological well-being within the past four weeks (e.g., death, divorce, etc.).

Individual participant data (IPD) will not be shared due to privacy and confidentiality concerns. The dataset contains sensitive clinical and psychological information of adolescent patients with cancer, and data sharing could risk participant identification. Only aggregated and anonymized results will be reported in publications.

Since the study will be conducted by the principal investigator, investigator blinding will not be possible. Additionally, because the study will be carried out with hospitalized adolescents and the intervention and control groups will be present in the clinic simultaneously, participant blinding cannot be implemented. To prevent potential bias in group allocation, the randomization table will be generated by an independent statistician. Data analysis and reporting will also be conducted by the same independent statistician, ensuring blinding at the statistical analysis stage.