Hospital admission for neurologic disorders among 5-year survivors of noncentral nervous system tumors in childhood: A cohort study within the Adult Life after Childhood Cancer in Scandinavia study.

Large, comprehensive studies of the risk for neurologic disorders among long-term survivors of noncentral nervous system (CNS) childhood cancers are lacking. Thus, the aim of our study was to assess the lifetime risk of Nordic non-CNS childhood cancer survivors for neurologic disorders. We identified 15,967 5-year survivors of non-CNS childhood cancer diagnosed in Denmark, Iceland, Finland and Sweden in 1943-2008, and 151,118 matched population comparison subjects. In-patient discharge diagnoses of neurologic disorders were used to calculate relative risks (RRs) and absolute excess risks (AERs). A neurologic disorder was diagnosed in 755 of the survivors while 370 were expected, yielding a RR of 2.0 (95% confidence interval (CI) 1.9-2.2). The highest risks were found among survivors of neuroblastoma (4.1; 95% CI 3.2-5.3) and leukemia (2.8; 95% CI 2.4-3.2). The AER decreased from 331 (278-383) excess neurologic disorders per 100,000 person-years 5-9 years after diagnosis to 82 (46-118) ≥ 20 years after diagnosis. Epilepsy was the most common diagnosis (n = 229, 1.4% of all survivors), and significantly increased risks were seen among survivors of eight out of 12 types of childhood cancer. Survivors of neuroblastoma had remarkably high risks (RR ≥ 10) for hospitalization for paralytic syndromes and hydrocephalus, while survivors of leukemia had additional high risks for dementia and encephalopathy. In conclusion, survivors of non-CNS childhood cancer are at high risk for neurologic disorders, especially within the first decade after diagnosis. Therefore, intensive follow-up to identify those who require close management is needed.