**Background:** Childhood cancer survivors (CCS) face an elevated risk of therapy-related chronic health conditions (late effects), necessitating risk-adapted long-term follow-up (LTFU) care. In Germany, over 40,000 5-year CCS are registered in the German Childhood Cancer Registry (GCCR), but only a few benefit from adequate clinical LTFU structures. To address this gap, a clinical LTFU database was developed in cooperation with the GCCR. This paper presents the feasibility of implementing this database at two German university centres (Luebeck and Berlin) and provides an initial analysis of the collected data.
**Methods:** The feasibility study enrolled 208 CCS aged ≥18 years who attended LTFU clinics between April 2021 and December 2022, with data entry completed by March 2023. Participants had survived ≥5 years after their first cancer diagnosis. Data were collected during routine LTFU or first clinic visits in adult care, including medical, mental, and psychosocial health information. CCS were stratified into three risk groups (RG) based on their individual risk for late effects: RG1 (low risk, n=40), RG2 (intermediate risk, n=52), and RG3 (high risk, n=116). The database captured seven categories: cancer diagnosis and treatment, health outcomes (e.g., endocrine, cardiac, pulmonary diseases), family history, psychosocial history, living situation, and validated self-report questionnaires (PHQ-9-D, GAD-7, NCCN distress thermometer, IES-R, EORTC QLQ-C30 and FA12). Descriptive statistics were performed using SPSS IBM Version 29, with comparisons across RG using Kruskal-Wallis and chi-square tests.
**Key Results:** The response rate was 98.1% (208/212). Mean age at inclusion was 26.5 years (range 18.0–60.0), with 62.5% aged 18–24 years. Mean time since diagnosis was 16.4 years (range 5.0–57.7). Primary diagnoses included leukaemia (36.5%), lymphoma (26.4%), CNS tumours (13.9%), bone/soft-tissue tumours (9.6%), embryonal tumours (5.8%), and others (7.7%). Chronic health conditions were prevalent: endocrinological disorders affected 54.3% (113/208) of CCS, cardiovascular disorders 36.2% (75/207), gut disorders 22.2% (46/207), ear–nose–throat disorders 14.6% (30/205), and pulmonary diseases 12.0% (25/208). The proportion of CCS with at least one health condition increased with risk group: for endocrinological disorders, 27.5% in RG1, 42.3% in RG2, and 69.0% in RG3 (p<0.001); for cardiovascular disorders, 22.5%, 21.2%, and 47.8% respectively (p=0.007). The number of affected organ systems also rose with RG: 0–8 systems per patient, with RG3 showing the highest burden. For example, endocrinological conditions ranged from 0 to 5 per CCS, with two-thirds of RG1 having none, while RG3 patients had up to five conditions. Specific endocrinological findings included vitamin D deficiency (39.3%), osteopenia (4.4%), and osteoporosis (1.5%). Subsequent neoplasms occurred in 5.8% (12/208), with skin cancer being the most common (50.0%).
**Clinical Implications:** This feasibility study confirms that a clinical LTFU database can be successfully implemented in German LTFU clinics, with high acceptance among CCS. The data reveal a substantial burden of chronic health conditions even in young adult CCS, underscoring the need for life-long, risk-adapted surveillance. The higher prevalence of late effects in RG3 supports the validity of the risk stratification model. The database will be expanded to over ten centres as part of the prospective LE-Na trial, aiming to enrol over 5000 CCS over 5 years. This infrastructure will enable standardized, longitudinal data collection for potentially over 40,000 German CCS, facilitating future national and international research to improve LTFU guidelines and care.