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BackgroundSurvivors of childhood cancer are at increased risk for a wide range of late effects. However, no large population-based studies have included the whole range of somatic diagnoses including subgroup diagnoses and all main types of childhood cancers. Therefore, we aimed to provide the most detailed overview of the long-term risk of hospitalisation in survivors of childhood cancer.Methods and findingsFrom the national cancer registers of Denmark, Finland, Iceland, and Sweden, we identified 21,297 5-year survivors of childhood cancer diagnosed with cancer before the age of 20 years in the periods 1943–2008 in Denmark, 1971–2008 in Finland, 1955–2008 in Iceland, and 1958–2008 in Sweden. We randomly selected 152,231 population comparison individuals matched by age, sex, year, and country (or municipality in Sweden) from the national population registers. Using a cohort design, study participants were followed in the national hospital registers in Denmark, 1977–2010; Finland, 1975–2012; Iceland, 1999–2008; and Sweden, 1968–2009. Disease-specific hospitalisation rates in survivors and comparison individuals were used to calculate survivors’ standardised hospitalisation rate ratios (RRs), absolute excess risks (AERs), and standardised bed day ratios (SBDRs) based on length of stay in hospital. We adjusted for sex, age, and year by indirect standardisation. During 336,554 person-years of follow-up (mean: 16 years; range: 0–42 years), childhood cancer survivors experienced 21,325 first hospitalisations for diseases in one or more of 120 disease categories (cancer recurrence not included), when 10,999 were expected, yielding an overall RR of 1.94 (95% confidence interval [95% CI] 1.91–1.97). The AER was 3,068 (2,980–3,156) per 100,000 person-years, meaning that for each additional year of follow-up, an average of 3 of 100 survivors were hospitalised for a new excess disease beyond the background rates. Approximately 50% of the excess hospitalisations were for diseases of the nervous system (19.1% of all excess hospitalisations), endocrine system (11.1%), digestive organs (10.5%), and respiratory system (10.0%). Survivors of all types of childhood cancer were at increased, persistent risk for subsequent hospitalisation, the highest risks being those of survivors of neuroblastoma (RR: 2.6 [2.4–2.8]; n = 876), hepatic tumours (RR: 2.5 [2.0–3.1]; n = 92), central nervous system tumours (RR: 2.4 [2.3–2.5]; n = 6,175), and Hodgkin lymphoma (RR: 2.4 [2.3–2.5]; n = 2,027). Survivors spent on average five times as many days in hospital as comparison individuals (SBDR: 4.96 [4.94–4.98]; n = 422,218). The analyses of bed days in hospital included new primary cancers and recurrences. Of the total 422,218 days survivors spent in hospital, 47% (197,596 bed days) were for new primary cancers and recurrences. Our study is likely to underestimate the absolute overall disease burden experienced by survivors, as less severe late effects are missed if they are treated sufficiently in the outpatient setting or in the primary health ca...

The lifetime risk for cardiovascular disease in a large cohort of childhood cancer survivors has not been fully assessed. In a retrospective population-based cohort study predicated on comprehensive national health registers, we identified a cohort of 32,308 one-year survivors of cancer diagnosed before the age of 20 in the five Nordic countries between the start of cancer registration in the 1940s and 1950s to 2008; 211,489 population comparison subjects were selected from national population registers. Study subjects were linked to national hospital registers, and the observed numbers of first hospital admission for cardiovascular disease among survivors were compared with the expected numbers derived from the population comparison cohort. Cardiovascular disease was diagnosed in 2,632 childhood cancer survivors (8.1%), yielding a standardized hospitalization rate ratio (RR) of 2.1 (95% CI 2.0-2.2) and an overall absolute excess risk (AER) of 324 per 100,000 person-years. At the end of follow-up 12% of the survivors were 50 years of age and 4.5% 60 years of age. Risk estimates were significantly increased throughout life, with an AER of~500-600 per 100,000 person-years at age 40. The highest relative risks were seen for heart failure (RR, 5.2; 95% CI 4.5-5.9), valvular dysfunction (4.6; 3.8-5.5) and cerebrovascular diseases (3.7; 3.4-4.1). Survivors of hepatic tumor, Hodgkin lymphoma and leukemia had the highest overall risks for cardiovascular disease, although each main type of childhood cancer had increased risk with different risk profiles. Nordic childhood cancer survivors are at markedly increased risk for cardiovascular disorders throughout life. These findings indicate the need for preventive interventions and continuous follow-up for this rapidly growing population.

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