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Research Question: Are children born after assisted reproductive technology (ART) at higher risk of developing Langerhans cell histiocytosis (LCH)?, Design: Records of children born after ART recorded by the UK Human Fertilisation & Embryology Authority were linked to National Registry of Childhood Tumours records to determine the number of children developing LCH. Calculated person-years at risk were used in conjunction with the incidence of LCH in the general population to determine the expected number of cases if the cohort had the same incidence as the general population with similar age and sex, over the same calendar years. The standardized incidence ratio (SIR) was derived as the ratio of observed to expected cases. Exact 95% CI were calculated., Results: In total, 118,155 children born after ART contributed 796,633 person-years follow-up (average follow-up 6.74 years). Eight cases of LCH were identified, compared with 3.75 cases expected (SIR 2.135, 95% CI 0.92-4.21; P = 0.074). Significantly more cases were associated with intracytoplasmic sperm injection (ICSI) (SIR 4.02, 95% CI 1.31-9.39) and male factor infertility (SIR 5.41, 95% CI 1.47-13.84). Most cases of LCH had single-system disease (n = 6)., Conclusions: This study found that significantly more cases of LCH were identified in children born after ICSI and in children whose parents had male factor infertility. A non-significant excess of cases in children born after ART was identified. Absolute excess risk was small. Given the rarity of LCH and the small number of cases included in this large cohort, further studies into the risk of LCH in children born after ART are indicated., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Patterns and risks of subsequent primary tumours (SPTs) among long-term survivors of childhood cancer have been extensively described, but much less is known about early SPTs (ESPTs) occurring within 5 years after initial diagnosis., Procedure: We carried out a population-based study of ESPTs following childhood cancer throughout Britain, using the National Registry of Childhood Tumours. The full study series comprised all ESPTs occurring among 56,620 children whose initial cancer diagnosis was in the period 1971-2010. Frequencies of ESPT were calculated for the entire cohort. For analyses of risk, follow-up began 92 days after initial diagnosis., Results: ESPT developed in 0.4% of children overall, 0.52% of those initially diagnosed at age less than 1 year and 0.38% of those diagnosed at age 1-14 years. Standardised incidence ratio (SIR) was 7.7 (95% confidence interval [CI]: 6.7-8.9), overall 9.5 (95% CI: 7.1-12.5) for children initially diagnosed in 1981-1990 and 6.5-7.5 for those from earlier and later decades. SIR by type of first cancer ranged from 4.4 (95% CI: 1.8-9.1) for Wilms tumour to 13.1 (95% CI: 7.7-21.0) for non-Hodgkin lymphoma. SIR by type of ESPT ranged from 2.0 (95% CI: 1.0-3.4) for acute lymphoblastic leukaemia to 66.6 (95% CI: 52.3-83.6) for acute myeloid leukaemia. Predisposition syndromes were known to be implicated in 21% of children with ESPT and suspected in another 5%., Conclusions: This study provides an overview of the patterns and risks of ESPTs in a large population where many children received therapy that is still in widespread use. Further research will be needed to monitor and understand changes in risk as childhood cancer treatment continues to evolve., (© 2023 Wiley Periodicals LLC.)

Background: Previous epidemiological studies have found positive associations between maternal infections and childhood leukaemia; however, evidence from prospective cohort studies is scarce. We aimed to examine the associations using large-scale prospective data., Methods: Data were pooled from six population-based birth cohorts in Australia, Denmark, Israel, Norway, the UK and the USA (recruitment 1950s-2000s). Primary outcomes were any childhood leukaemia and acute lymphoblastic leukaemia (ALL); secondary outcomes were acute myeloid leukaemia (AML) and any childhood cancer. Exposures included maternal self-reported infections [influenza-like illness, common cold, any respiratory tract infection, vaginal thrush, vaginal infections and urinary tract infection (including cystitis)] and infection-associated symptoms (fever and diarrhoea) during pregnancy. Covariate-adjusted hazard ratio (HR) and 95% confidence interval (CI) were estimated using multilevel Cox models., Results: Among 312 879 children with a median follow-up of 13.6 years, 167 leukaemias, including 129 ALL and 33 AML, were identified. Maternal urinary tract infection was associated with increased risk of any leukaemia [HR (95% CI) 1.68 (1.10-2.58)] and subtypes ALL [1.49 (0.87-2.56)] and AML [2.70 ([0.93-7.86)], but not with any cancer [1.13 (0.85-1.51)]. Respiratory tract infection was associated with increased risk of any leukaemia [1.57 (1.06-2.34)], ALL [1.43 (0.94-2.19)], AML [2.37 (1.10-5.12)] and any cancer [1.33 (1.09-1.63)]; influenza-like illness showed a similar pattern but with less precise estimates. There was no evidence of a link between other infections and any outcomes., Conclusions: Urinary tract and respiratory tract infections during pregnancy may be associated with childhood leukaemia, but the absolute risk is small given the rarity of the outcome., (© The Author(s) 2021; all rights reserved. Published by Oxford University Press on behalf of the International Epidemiological Association.)