BACKGROUND: Fear of progression (FoP) is among the most prevalent psychosocial burdens in paediatric oncology. Empirical evidence suggests that FoP is particularly pronounced during acute treatment and often persists into follow-up care. It is associated with heightened perception of physical symptoms, increased post-traumatic stress symptoms, more negative illness perceptions, and reduced quality of life (QoL). Consequently, a comprehensive diagnostic instrument is essential to assess FoP in children with cancer.

OBJECTIVE: This study aimed to prospectively validate the German self-report version of the Fear of Progression Questionnaire for Children (FoP-Q-SF/C) aged 7-18 years both during acute treatment and in follow-up care.

METHODS: A total of 116 children participated in the study, including 39 undergoing acute treatment and 77 in follow-up care. Participants completed the FoP-Q-SF/C. Factor analyses were conducted, and associations between FoP and QoL, illness perceptions, posttraumatic stress symptoms, time since diagnosis, cancer type and treatment modality were examined.

RESULTS: All items were applicable in children. The FoP-Q-SF/C demonstrated high internal consistency and good convergent, criterion and divergent validity. Consistent with previous research, factor analysis supported a one-factor structure, although findings suggest potential for structural refinement.

CONCLUSIONS: The FoP-Q-SF/C is a reliable and valid questionnaire for assessing FoP in children with cancer across different treatment phases. It serves as a valuable screening instrument to identify children at risk for elevated psychosocial distress and to guide targeted psychosocial interventions.