New research published last week in the journal Nature gives us some insight into the molecular reasons why UV light causes skin cancer, and also key evidence that sunscreen doesn’t completely protect against UV damage to the skin (1). As we head into the summer months, this information is vital to protecting yourself against skin damage, so read on.
Malignant melanoma is the type of skin cancer that kills. This year, there are expected to be 76,100 new cases in the United States, with 9,710 deaths (2). Almost all of these cancer cases and deaths are preventable through sun protection. The worrying thing is that malignant melanoma is becoming increasingly common. Either we are becoming less careful with sunscreen in pursuit of golden brown sun-kissed skin, or else UV light from the sun is getting stronger over time. Perhaps it’s both. Either way, if you are a human with skin who doesn’t shut themselves up indoors all day, you need to look out for yourself.
Our bodies are smart, and we have built-in genes that protect us from sun damage. For example, freckles, which are genetically-based, form because the skin is producing extra melanin (pigment) to cover up and protect our fragile DNA from UV light. However, before this new research in Nature, we didn’t really know how UV light causes skin cancer at a molecular level. The researchers found that the UV light caused mutations in a gene called Trp53, a so-called ‘tumour suppressor’ gene as it is one of our bodies natural protections against cancer. Professor Richard Marais, the lead investigator on the research, said,
“UV light targets the very genes protecting us from its own damaging effects, showing how dangerous this cancer-causing agent is” (3)
Most importantly for your day-to-day life is the finding that sunscreen doesn’t provide full protection against these DNA-damaging effects of UV sunlight. Their research, using mice at risk of skin cancer, found that SPF 50 sunscreen did not protect against the development of melanoma with UV sunlight exposure. This means that, although sunscreen protects us against sunburn, it might not protect against skin cancer. Of course, this research was conducted in mouse models and not among humans (it would be unethical among humans), but the research seems compelling and is already causing a big media splash.
Of course, the media attention is warranted. Skin cancer causes a huge amount of unnecessary pain and mortality each year, and we can do a lot to prevent it. The results of this study led Professor Richard Marais to conclude,
“This work highlights the importance of combining sunscreen with other strategies to protect our skin, including wearing hats and loose fitting clothing, and seeking shade when the sun is at its strongest” (3)
Never forget that as long as you are in the sun, you are at risk for skin cancer. Also, don’t forget about the awful ageing effect that the sun can have on your skin. No one wants unnecessary wrinkles, sun spots, and that overall leathery shoe look. Because melanoma often starts from a dark freckle or mole, keep an eye on your moles with the ABC’s:
- Asymmetry: The shape of one half does not match the other half.
- Border that is irregular: The edges are often ragged, notched, or blurred in outline. The pigment may spread into the surrounding skin.
- Colour that is uneven: Shades of black, brown, and tan may be present. Areas of white, grey, red, pink, or blue may also be seen.
- Diameter: There is a change in size, usually an increase. Melanomas can be tiny, but most are larger than the size of a pea (larger than 6 millimetres or about 1/4 inch).
- Evolving: The mole has changed over the past few weeks or months.
The US National Cancer Institute also has a lovely collection of pictures of what melanoma looks like.
Take care of yourself, and have a good summer!
1) Viros A, Sanchez-Laorden B, Pedersen M, Furney SJ, Rae J, Hogan K, et al. Ultraviolet radiation accelerates BRAF-driven melanomagenesis by targeting TP53.
2) National Cancer Institute. Melanoma. http://www.cancer.gov/cancertopics/types/melanoma (accessed 12 June 2014).
3) Briggs H. Skin cancer: Sunscreen ‘not complete protection’. BBC. 11 June 2014. http://www.bbc.co.uk/news/health-27793354 (accessed 12 June 2014).
Image source: Micolo J via Flickr CC BY 2.0