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Some childhood cancer 30% less likely in parts of California with more UVB – April 2013

Solar UV radiation and cancer in young children

Christina A. Lombardi 1, Julia E. Heck 2, Myles Cockburn 3, and Beate Ritz 4,*
1 Epidemiology, UCLA Fielding School of Public Health
2 School of Public Health, University of California
3 Preventive Medicine, University of Southern California
4 UCLA Fielding School of Public Health
↵* Corresponding Author: Beate Ritz, UCLA Fielding School of Public Health, United States britz at ucla.edu

Background: Studies have shown that higher UV radiation exposure (UVR) may be related to lower risk of some cancers in adults. Recently an ecological study reported lower risks of some cancers among children living in higher UVR cities and countries. In a large population-based case-control study in California we tested the hypothesis that specific childhood cancers may be influenced by UVR.

Methods: Cancers in children ages 0 to 5 years were identified from California Cancer Registry records for 1986-2007 and linked to birth certificate data. Controls - frequency matched by year of birth - were sampled from the birth certificates at a ratio of 20:1. Based on the birth address, we assigned UVR exposure in units of Watt-hours/m2 to subjects using a geostatistical exposure model developed with data from the National Solar Radiation Database.

Results: For cases with UVR exposure of 5111 Watt-hrs/m2 or above we estimated a reduction in odds of developing

  • acute lymphoblastic leukemia (OR: 0.89, 95% CI:0.81, 0.99),
  • hepatoblastoma (OR: 0.69, 95% CI: 0.48, 1.00), and
  • non-Hodgkin's lymphoma (OR: 0.71, 95% CI: 0.50, 1.02)

adjusting for mother's age, mother's race and child's year of birth.

Conclusions: Our findings suggest that UVR during pregnancy may decrease the odds of some childhood cancers. Future studies should explore additional factors that may be correlated with UVR exposure, investigate trimester-specific effects and possibly include biomarkers of immune function and vitamin D to investigate possible pathways for the observed associations. Impact: This study shows protective associations of UVR and some childhood cancers.

Received November 28, 2012. Revision received February 15, 2013. Accepted April 4, 2013.

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