This blog is part of our community-sponsored blog series. Due to their generous support, this individual was able to select a topic meaningful to them and take part in crafting this blog. We thank them and all of our donors for their continued support.
Rita Celone Umile holds an MS degree in Labor Relations, and has the heart of an activist. Currently working in the field of public health, she considers herself very fortunate to be part of a team dedicated to resolving global public health issues. Rita has an innate curiosity regarding the impact of nutrition upon health and well-being. From this interest stems her extreme passion for ending vitamin D deficiency. To help achieve this goal, she spends many hours talking with folks interested in learning about the benefits of vitamin D and sunshine.
Rita has been an active member of the Vitamin D Council since 2012. In her own words, “The Vitamin D Council is an impeccable nonprofit organization that provides accurate, up-to-date and unbiased information on a deficiency that is still not taken seriously by much of mainstream medicine.” She contributed to our blog on melanoma in honor of mother, Noemi Celone, an over 20-year survivor of this deadly disease, and the person who first introduced her to the amazing work of Dr. John Cannell.
A study published over the summer of 2014 found that occupational sun exposure does not lead to an increased risk of melanoma.
Occupational sun exposure is frequent, continuous sun exposure, as opposed to intermittent sun exposure. This is the type of sun exposure seen in hunter-gatherer populations, which receive consistent sun exposure when sunlight is available.
The relationship between sun exposure and melanoma is complex. Previous research has revealed sunburn and intermittent sun exposure are associated with an increased risk of melanoma. On the other hand, studies examining the relationship between occupational sun exposure and melanoma have found no or inverse associations.
Melanoma is a type of skin cancer thought to be caused by multiple genetic and environmental factors and its relationship with sun exposure is suggested to differ by the site of cancer and the pattern of sun exposure.
There is some evidence to suggest that melanoma on the head and neck is related to continuous sun exposure, whereas melanoma that is located on the trunk and limbs is associated with intermittent sun exposure.
It is important to clarify the relationship between different types of sun exposure, areas the body exposed, and melanoma in order to ensure that health organizations make accurate and informed decisions when it comes to sun protection policy.
Researchers therefore decided to conduct a study analyzing data from two large, population-based case-control studies: the Australian Melanoma Family Study (AMFS) and the international Genes, Environment and Melanoma (GEM) study.
The AMFS is a multi-center, population based, case-control study that recruited, between 2001 and 2005,over 629 individuals with early-onset melanoma diagnosed before the age of 40 as well as 295 spouses or relatives and 240 individuals without melanoma to serve as controls. The aim of the study was to determine the contribution of genes and environment to melanoma incidence in populations from three different cities in Australia.
The GEM study is an ongoing population-based international consortium initiated in 1998 that is studying risk for melanoma development and progression and the role of sun exposure and genetics in melanoma. It currently consists of 3,700 individuals from the U.S., Canada, Italy, and Australia.
Both studies used self-administered and telephone-administered questionnaires to collect data on demographics, skin color, and sun exposure behavior.
The researchers used this data to determine a comprehensive view of sun exposure behavior, risk of melanoma, and site of melanoma.
Separate analyses on the two sets of data from the two case-controls yielded the following results:
- In the AMFS, there was no association between occupational sun exposure and melanoma risk overall, and no association was found between occupational sun exposure and the anatomical site of the melanoma.
- In the GEM study, there was a negative association between total weekday sun exposure and melanoma on the head and neck, meaning higher weekday sun exposure led to a decreased risk of melanoma at these sites.
- After adjusting for weekend sun exposure in both case-controls, there was no association between total sun exposure and overall melanoma risk or melanoma at different sites.
- In both studies, melanoma risk tended to be higher for people who had intermittent patterns of exposure.
The researchers summarized their findings by saying,
“We observed no consistent association between occupational sun exposure and melanoma risk overall and little evidence that this association varied by anatomical site. We observed no increase or decrease in melanoma risk in those with high levels of both weekday and weekend sun exposure (i.e., high continuous pattern of sun exposure) overall or for melanoma of the head and neck. There was, however, evidence that those who had intermittent patterns of exposure (‘high weekday, low week- end’ and ‘low weekday, high weekend’ categories) had increased risk of melanoma.”
The research team noted that the lack of association between occupational sun exposure and melanoma could be from the protective actions of melanin. Melanin absorbs ultraviolet radiation and mitigates its harmful effects. More continuous sun exposure increases both melanin production and the thickness of the skin, both of which are thought to protect against the damaging effects of UV radiation.
The most conspicuous limitation is the use of sun exposure data gathered from self-administered and retrospective questionnaires, which can lead to considerable measurement errors.
Skin type could have impacted the results, as fair skinned individuals self-select jobs that involve less sun exposure. Although the researchers did adjust for skin color and skin response to sun exposure, they were not able to adjust for skin phenotype.
These results provide more evidence that the relationship between melanoma and sun exposure is nuanced, and that a certain amount of consistent sun exposure may be protective against this skin cancer. The results also provide evidence against the notion that occupational sun exposure may increase the risk of melanomas on the head and neck.
Future studies looking to validate these results should include prospective cohort studies that correct for the limitations seen in this study and track sun exposure and development of melanoma over a long period.