Globally, an estimated 400,000 children and adolescents are diagnosed with cancer each year (WHO, 2022). In Turkey, the incidence of childhood cancer is reported to be approximately 2500–3000 per year (Kebudi & Alkaya, 2021). Childhood cancers affect children and adolescents of all ages physically and psychosocially (Blaney et al., 2021; Hinds et al., 2023; Jibb et al., 2022). The critical developmental period between the ages of eight and eighteen is when self-efficacy, resilience, and coping mechanisms are actively shaped, especially (Hockenberry et al., 2022; Santrock, 2019). The importance of self-efficacy in the lives of children and adolescents during this critical life stage significantly determines their ability to overcome developmental milestones and the multifaceted challenges associated with the cancer experience (Jibb et al., 2021; Thornton et al., 2021).

The concept of self-efficacy, based on Bandura's social learning theory, reflects individuals' belief in their capacity to face and overcome certain situations (Bandura, 1982). Self-efficacy, which, along with Bandura's social learning theory, is also considered a foundational concept in health behavior change, is an essential component of several theories and frameworks that guide behavioral changes for better health and well-being (Wood & Bandura, 1989). Children and adolescents with these special needs face unique challenges, including treatment-related physical and psychological symptoms, disruptions in education, and changing social dynamics (Freedman et al., 2023). Addressing these challenges requires a nuanced understanding of their general self-efficacy, which is crucial for sustaining health-related behavior changes and managing symptoms in children and adolescents.

Despite recent advances in evidence-based treatment approaches and technological advances in pediatric cancers (Wyatt et al., 2023), psychological dimensions of self-efficacy, coping, and resilience in children and adolescents affected by the disease are limited in the literature (Paterson et al., 2023). The present literature mainly focuses on the management of physical symptoms of pediatric cancers, with limited attention to the psychosocial aspects that profoundly affect children and adolescents' self-efficacy, coping, and adaptability (Lim & Shorey, 2019; Melesse et al., 2022). Also, the limited number of validated measurement tools developed specifically for this age group underscores the need for a comprehensive and reliable instrument to assess self-efficacy (Kwak et al., 2021). Understanding pediatric cancer patients' self-efficacy is essential for developing targeted interventions to improve coping mechanisms, contribute to better psychological outcomes, and ultimately facilitate a more holistic approach to their care (Kwak et al., 2021; Pitt et al., 2023).

As children and adolescents aged eight to eighteen years face unique psychosocial challenges during cancer treatment, with limited coping and self-management skills and intense symptoms, it becomes essential to understand the role of self-efficacy specific to this age group. In the current literature, there are limited instruments assessing self-efficacy in children and adolescents aged eight to eighteen years undergoing cancer treatment (Liu et al., 2020; Wang, 2001). However, while there are psychometric studies in Turkey to assess self-efficacy in adolescents aged ten to seventeen years with chronic diseases (Gürcan & Turan, 2022), there is no valid and reliable measurement tool to assess the self-efficacy level of children and adolescents aged eight to eighteen years under cancer treatment. The lack of validated tools for this age group emphasizes the need for a comprehensive and reliable tool to assess general self-efficacy. This study aimed to assess the validity and reliability of the Turkish version of the General Self-Efficacy Scale in children and adolescents aged 8–18 years undergoing cancer treatment and to test its psychometric properties.