Sunscreen alone 'not enough' to protect against melanoma

This year, approximately 76,100 new cases of melanoma will be diagnosed - the deadliest form of skin cancer. Since exposure to ultraviolet light - from the sun and tanning beds - is a major risk factor for melanoma, wearing sunscreen is top of the list as a prevention aid. But now, a new study published in the journal Nature suggests that sunscreen alone is not enough to protect against the disease.

Melanoma is a major concern in the US, with rates of the disease increasing for at least 3 decades. In an attempt to reduce the skin cancer burden, public health campaigns worldwide are trying to encourage people to cover up in the sun, as well as wear sunscreen on exposed areas of skin.

For example, the National Council on Skin Cancer Prevention has declared the Friday before Memorial Day as "Don't Fry Day" - a campaign that aims to raise awareness of overexposure to ultraviolet (UV) radiation.

This latest study - conducted by The University of Manchester's Cancer Research UK Institute and the Institute of Cancer Research, also in the UK - supports such campaigns.

UV light targets damage-preventing genes, even with sunscreen on

To reach their findings, the research team analyzed the effects of UV light on 2-month-old mice with an abnormal BRAF gene, which is known to increase the risk of melanoma.

The researchers found that on unprotected skin, UV light directly damages the DNA of pigment cells in the skin, which raises the risk of melanoma. Specifically, the team discovered that exposure to UV light leads to abnormalities in a gene called p53, which usually works to prevent DNA damage from UV radiation.

After applying sunscreen to the skin of the mice, the team found it significantly reduced the level of DNA damage caused by UV radiation, which slowed development of melanoma.

However, the researchers also found that sunscreen failed to offer total protection from UV light and that the radiation was still able to cause abnormalities in the p53 gene, just at a lower rate.

Commenting on the findings,scientists at Cancer Research UK, say:

"UV light has long been known to cause melanoma skin cancer, but exactly how this happens has not been clear. These studies allow us to begin to understand how UV light causes melanoma.

UV light targets the very genes protecting us from its own damaging effects, showing how dangerous this cancer-causing agent is. Very importantly, this study provides proof that sunscreen does not offer complete protection from the damaging effects of UV light."

The importance of protecting against UV light

The scientistis at Cancer Research UK, note that although sunscreen - when applied properly - can protect against UV radiation, people tend to "think they're invincible" once they have put it on and spend longer in the sun. As a result, overall exposure to UV light is increased.

As well as wearing sunscreen, the National Council on Skin Cancer Prevention recommend seeking shade when the sun is at its strongest and wearing sun-protective clothing

"This research adds important evidence showing that sunscreen has a role, but that you shouldn't just rely on this to protect your skin," she adds. "It's essential to get into good sun safety habits, whether at home or abroad, and take care not to burn - sunburn is a clear sign that the DNA in your skin cells has been damaged and, over time, this can lead to skin cancer."

As well as applying generous amounts of sunscreen - SPF 30 or higher - when in the sun, the National Council on Skin Cancer Prevention recommend seeking shade when the sun is at its strongest and wearing sun-protective clothing, such as a wide-brimmed hat, wrap-on sunglasses and a T-shirt.

Scientistis recently reported on a study published in the journal Cancer Epidemiology, Biomarkers & Prevention, which suggests that five or more blistering sunburns experienced before the age of 20 could increase the risk of melanoma by 80%.