Background Incidence rates in Denmark of central nervous system (CNS) tumors remain among the highest in the world. Survival rates, however, have improved in the past decades in high‐income countries. Methods We analyzed incidence and survival of childhood CNS tumors in Denmark diagnosed from 1997 to 2019 based on data from the Danish Childhood Cancer Registry and information on histological types, tumor localization, and treatment from medical records. Results From 1997 to 2019, 949 children<15 years were diagnosed with a CNS tumor. Age‐standardized incidence was 42.1 (95% CI, 39.4–44.6) per million person‐years and stable during this period. Age‐specific incidence for children aged 0–4 years was 47.7 per million. More than one‐third (n = 374, 39.4%) were treated with surgery alone. Overall survival rates 5 and 10 years after diagnosis were 77.6% (95% CI, 74.7–80.2) and 74.7% (95% CI, 71.7–77.5). Five‐year overall survival improved from 73.0% (95% CI, 68.9–76.7) in 1997–2008 to 83.2% (95% CI, 79.2–86.4) in 2009–2019 (p‐value < 0.0001) in children aged 0–4 years (p = 0.0006). Conclusion Incidence rates are stable but remain among the highest in the world. Despite improved survival rates in recent years in younger children, some subtypes still have a poor prognosis.

BackgroundTumors of the central nervous system (CNS) are the most common solid childhood malignancy. Over the last decades, treatment developments have strongly contributed to the improved overall 5-year survival rate, which is now approaching 75%. However, children now face significant long-term morbidity with late-effects including sleep disorders that may have detrimental impact on everyday functioning and quality of life. The aims of this study were to (1) describe the symptoms that lead to polysomnographic evaluation; (2) describe the nature of sleep disorders diagnosed in survivors of childhood CNS tumor using polysomnography (PSG); and (3) explore the association between tumor location and diagnosed sleep disorder.MethodsAn extensive literature search following the Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines (PRISMA) was conducted. Inclusion criteria were children and adolescents diagnosed with a CNS tumor age &lt;20 years having a PSG performed after end of tumor treatment. The primary outcome was sleep disorder confirmed by PSG.ResultsOf the 1,658 studies identified, 11 met the inclusion criteria. All the included articles were appraised for quality and included in the analysis. Analyses indicated that sleep disorders commonly occur among childhood CNS tumor survivors. Symptoms prior to referral for PSG were excessive daytime sleepiness (EDS), fatigue, irregular breathing during sleep and snoring. The most common sleep disorders diagnosed were sleep-related breathing disorders (i.e., obstructive sleep apnea) and central disorders of hypersomnolence (i.e., narcolepsy).ConclusionOur findings point to the potential benefit of systematically registering sleep disorder symptoms among CNS tumor patients together with tumor type and treatment information, so that at-risk patients can be identified early. Moreover, future rigorous and larger scale controlled observational studies that include possible modifiable confounders of sleep disorders such as fatigue and obesity are warranted.Clinical Trial Registrationhttps://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021243866, identifier [CRD42021243866].

To ensure external validation of a study population in clinical late-effect studies of childhood cancer, the participation rate must be high. This study investigated demographic data in Nordic late-effect studies and potential factors impacting participation rates such as cancer type, time since diagnosis, and duration of clinical examinations.We found 80 published studies originating from 16 cohorts, with median follow-up of 6.0 years (range 3-14). The overall participation rates ranged from 27% to 100%. The highest participation rates were seen in studies of survivors with solid tumors (92%) and the lowest in hematologic malignancies (67%) and central nervous system tumors (73%). The clinical examination in 10 studies (62.5%) lasted for more than 3 hours.Neither duration of the clinical examination nor time since diagnosis seemed to affect the participation rate. We encourage future studies to describe the recruitment process more thoroughly to improve understanding of the factors influencing participation rates.