Study shows association with high birth weights, childhood UV exposure and early age melanoma.
This was a population-based, case-control study that analysed the effects of birth weight and infant to early life ultraviolet (UV) radiation exposure on the risk of melanoma in children, adolescents and young adults in the state of California, United States of America. The study compared 1396 cases of melanoma diagnosed before the age of 30 from 1988 to 2013 and 27 920 controls. Birth weights were obtained from birth records and UV exposure was assigned based on measurements of environmental UV levels in the place of birth. Cases and controls were further categorised by other factors such as race, ethnicity, gender and gestational age in order to account for adjust for these variables in the population.
The authors reported an overall increased risk of melanoma for birthplaces where UV levels were higher. The risk was highest in people aged over 15 years where one group exposed to higher UV levels showed an 85% increase in melanoma risk (Odds ratio, OR: 1.85; 95% Confidence Interval, CI: 1.37, 2.50). However, the overall relationship did not show a clear trend of increasing risk with increasing UV levels. It was also reported that a birthweight greater than 4000 grams was associated with a 19% higher risk of melanoma and birth weights less than 2500 grams were associated with a 41% lower risk of melanoma. There was also evidence of a dose response where the risk increased per 1000 grams. The authors identified that the UV exposure data was limited in that it did not account for sun exposure based on factors such as behaviour, occupation, migration etc. The increased risk of melanoma in high birthweight cases was attributed to a greater surface area of skin being expose to UV from infancy.
Overall, the results reported by the authors support ARPANSA’s sun protection messaging. Further, the study has indicated that birth weights may change the risk of melanoma development at a young age. Despite the limitations in the data used to assess UV exposure, the results indicate that sun protection may be advised from infancy.