Early UVA light exposure 'doesn't cause melanoma'

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Washington, May 5 (ANI): Scientists from The University of Texas MD Anderson Cancer Center have found that early life exposure to ultraviolet A light does not cause melanoma.

The researchers, therefore, concluded that UVA exposure is unlikely to have contributed to the rise in the incidence of melanoma over the past 30 years.

UVA is a carcinogen responsible for squamous cell carcinomas that also causes premature aging of the skin and suppresses the immune system. It's also possible, the authors note, that long-term chronic exposure to UVA can hasten the progression to malignancy of melanocytes in the skin that are already on the path to becoming melanoma.

Study's lead author David Mitchell, professor in M. D. Anderson's Department of Carcinogenesis located at its Science Park - Research Division in Smithville, Texas, and colleagues tested the effects of UVA and ultraviolet B (UVB) light exposure in melanoma-prone fish hybrids that develop the disease spontaneously 15-20 percent of the time without exposure to UV light.

The scientists exposed a hybrid form of the genus Xiphophorus, more commonly known as platyfishes and swordtails, to either UVA or UVB daily between their fifth and 10th day of life. The fish were then scored for melanoma 14 months after exposure.

"We found that UVB exposure induced melanoma in 43 percent of the 194 treated fish, a much higher rate than the 18.5 percent incidence in the control group that received no UV exposure," Mitchell said.

This was expected because UVB exposure at an early age is a well-established cause of melanoma.

Only 12.4 percent of 282 fish exposed to UVA developed the disease, which is not statistically different from the control group.

The study has been reported in the online early edition of the Proceedings of the National Academy of Sciences. (ANI)

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