Residential exposure to solar ultraviolet radiation and risk of childhood hematological malignancies in Switzerland: A census-based cohort study.

in International journal of cancer by Astrid Coste, Christian Kreis, Claudine Backes, Jean-Luc Bulliard, Christophe Folly, Eva Brack, Raffaele Renella, David Vernez, Ben D Spycher,

TLDR

  • The study found an inverse association between solar UVR exposure and childhood ALL risk, supporting a potential cancer risk reduction strategy.
  • The findings highlight the need for further research on environmental risk factors and the molecular mechanisms underlying this association.

Abstract

Still little is known about possible environmental risk factors of childhood hematological malignancies (CHM). Previous studies suggest that ultraviolet radiation (UVR) exposure is associated with a lower risk of acute lymphoblastic leukemia (ALL) in children. We investigated the association between solar UVR exposure and risk of CHM in Switzerland, a country with greatly varying topography and weather conditions. We included all resident children aged 0-15 years from the Swiss National Cohort during 1990-2016 and identified incident cancer cases through probabilistic record linkage with the Swiss Childhood Cancer Registry. We estimated the overall annual mean UV level and the mean level for the month of July during 2004-2018 at children's homes using a climatological model of the midday (11 am-3 pm) UV-index (UVI) with a spatial resolution of 1.5-2 km. Using risk-set sampling, we obtained a nested case-control data set matched by birth year and fitted conditional logistic regression models (virtually equivalent to analyzing full cohort data using proportional hazards models) adjusting for sex, neighborhood socio-economic position, urbanization, air pollution, and background ionizing radiation. Our analyses included 1446 cases of CHM. Estimated adjusted hazard ratios (HR) per unit increase in UVI in July were 0.76 (95% CI 0.59-0.98) for leukemia and 0.74 (0.55-0.98) for ALL. Results for annual exposure were similar but confidence intervals were wider and included one. We found no evidence for an association for lymphoma overall (HR 1.14, 95% CI 0.59-2.19 for annual exposure) or diagnostic subgroups. Our study provides further support for an inverse association between exposure to ambient solar UVR and childhood ALL.

Overview

  • The study investigated the association between solar ultraviolet radiation (UVR) exposure and the risk of childhood hematological malignancies (CHM) in Switzerland.
  • The study included all resident children aged 0-15 years from the Swiss National Cohort during 1990-2016 and identified incident cancer cases through record linkage with the Swiss Childhood Cancer Registry.
  • The primary objective of the study was to examine the inverse association between exposure to ambient solar UVR and childhood acute lymphoblastic leukemia (ALL).

Comparative Analysis & Findings

  • The study found an inverse association between exposure to ambient solar UVR and childhood acute lymphoblastic leukemia (ALL), with estimated adjusted hazard ratios (HR) per unit increase in UVI in July of 0.76 (95% CI 0.59-0.98).
  • Similar results were observed for annual exposure, with confidence intervals wider and including one.
  • No evidence of an association was found for lymphoma overall or diagnostic subgroups.

Implications and Future Directions

  • The study provides further support for an inverse association between exposure to ambient solar UVR and childhood ALL, with potential implications for cancer risk reduction strategies.
  • Future studies should investigate the molecular mechanisms underlying this association and consider the potential impacts of air pollution and background ionizing radiation.
  • Additionally, the study highlights the need for further research on the environmental risk factors of childhood hematological malignancies, including other environmental pollutants and lifestyle factors.
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