Article review data
August 2024
Article publication date
February 2024
ARPANSA summary
This cohort study examined the association between ultraviolet radiation (UVR) and childhood acute lymphocytic leukaemia (ALL) and childhood non-Hodgkin lymphoma (NHL). The study included 30,349 cases of ALL and 8062 cases (aged <20 years old) of NHL collected from population-based cancer registries (SEER 2022) for the years 2000-2020. The study adjusted for sex, median rent, calendar year, age and racial/ethnic group. UVR exposure data were collected from the measurements of 239 UVR measurement stations, which provided exposure measures of average solar UVR (mW/cm2) and cumulative solar UVR exposure (MJ/cm2). The authors reported an association between ALL incidence and UVR (relative risk (RR) 1.2/mW/cm2 (95% confidence interval (CI) 1.06-1.36)), but significant decreasing trends for NHL (RR 0.6/mW/cm2 (95% CI 0.51-0.82)). There was no increasing trend for cumulative UVR exposure for ALL (RR = 1.44/MJ/cm2 95% CI 0.95-2.2) but again there was a decreasing trend for NHL (RR = 0.28/MJ/cm2 95% CI 0.166-0.49). The study concluded that high UVR exposure could be associated with ALL, however, the evidence was not strong enough to make firm conclusions.
Link to study
Published in
British Journal of Cancer
ARPANSA commentary
The authors reported an association between ALL incidence and UVR exposure. There is disagreement in the literature surrounding the association between ALL and UVR exposure. A French study reported that for children aged less than 5 years old there was an increasing trend of ALL for each 25 J/cm2 of UVR exposure (standardized incidence ratio 1.18; 95% CI 1.10-1.27) (Coste et al 2015). However, a Californian study reported a reduction in the risk of ALL with UVR exposure of ≥5,111 W/h/m2 (odds ratio 0.89, 95% CI: 0.81-0.99) for children under 5 years old (Lombardi et al 2013). Overall, it remains unclear if UVR exposure increases the risk of ALL. The study also reported a protective effect of solar UVR exposure on childhood NHL. This has been reported in previous studies and has been assessed in systematic reviews. The systematic reviews have reported contradictory results that UVR exposure reduced the risk of NHL in children and adults (Kim and Kim 2021) and increased the risk of NHL in people aged 17 and above (Lu et al 2017). Overall, the evidence for an effect of UVR exposure on NHL is unclear.
A major limitation of this study and those by Lombardi et al (2013) and Coste et al (2015) is that they do not examine UVR exposure at the individual level. The actual UVR a person is exposed to could deviate significantly from the average solar UVR depending on how much time they spend outside each day and their occupation. None of these factors were considered by the authors. This could result in misclassification bias where the people in the low exposure group could have high exposure and those in the high exposure group could have low exposure.
Given high UVR exposure in Australia compared to many parts of the world, ARPANSA recommends adoption of the 5 sun protection principles (i.e. Slip, Slop, Slap, Seek, Slide) when the UV Index is 3 or more. ARPANSA administers and maintains UVR monitoring stations across Australia that can be used to measure the UV Index in real-time and provide sun protection recommendation to the general public on a daily basis.
