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UVA and UVB exposure: Increase risk of melanoma?

Posted on: May 21, 2012   by  Kate Saley


UV exposure’s role in skin cancer has always been a hot topic in vitamin D research. As you can pick up on all of our blogs this week, research in the area is contradictory, so much is still to be learned on the topic of sun exposure and skin cancer.

Professor Moan and colleagues recently studied UVA and UVB exposure and incidence rates of cutaneous malignant melanoma (CMM) and squamous cell carcinoma (SCC) in Norway and Sweden to lo see if there is a relationship.

Moan J, Baturaite Z, Porojnicu AC, Dahlback A, and Juzeniene A. UVA, UVB and incidence of cutaneous malignant melanoma in Norway and Sweden. Photochemical & Photobiological Sciences. 2012.

Moan and company reviewed data from the Cancer Registries from Norway and Sweden to find the incidence of CMM and SCC in different counties, as well as collect data on UVA and UVB. They found:

  • Incidence of CMM and SCC among men and women are increasing in Norway and Sweden.
  • The incidence rates of CMM in both sexes increase with decreasing latitude.
  • The incidence rates for CMM in people under 50 years of age have decreased or stayed constant after about 1990, notably in the southern region of Norway.
  • The UVA/UVB ratio decreases with decreasing latitude, as does the CMM/SCC ratio of incidence rates.

Based on the last finding, the authors suggest that UVA may contribute to melanoma more so than to squamous cell carcinoma. In other words, there are a higher percentage of UVA rays at higher latitudes than at lower latitudes and that could explain why there are relatively more CMM cases to SCC cases at the higher latitudes compared to lower latitudes.

They recommend future research confirm their findings, and if confirmed, they suggest better UVB to UVA ratios in sunbeds. They also denounce the use of sunscreens that block UVB but not UVA. And they acknowledge the importance of keeping vitamin D levels sufficient year round.

“Sun-like sunbeds, with less UVA than those used now, would act as summer sun and might, carefully used, improve the winter levels of vitamin D. Keeping a constant vitamin D level throughout the year might be optimal.”

This is in line with what the Vitamin D Council recommends: exposure to sunlight or low pressure tanning beds that focus on the UVB spectrum, which allows your skin to produce vitamin D.

1 Response to UVA and UVB exposure: Increase risk of melanoma?

  1. theguru

    Very important information and a good first step towards full-spectrum lamps in tanning beds. However, we should not look away from that the increased diagnosis of CMM and CSS also might be due to an intensified screening. This is definitely the case in USA, very well described by Prof. Glusac in his report “The melanoma ‘epidemic’, a dermatopathologist’s perspective”, from December 2010.
    For more info about the creation of sun-scare by inflated diagnoses of skin-cancer, see here:
    The Creation of Sun-Scare
    The Melanoma awareness month (or week/days/day, depending in which country) is one of the ways used by the founders of sun-scare to inflate the statistics. It is described quite well here:
    Melanoma Day: It’s Scary… But Not In The Way You Might Think

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