This is How the Sun Causes Skin Cancer

This might come as a surprise: While we’ve known for a while that exposure to the sun’s UV rays could lead to skin cancer, it wasn’t until recently that we understood exactly how that process worked.

Before I get to the groundbreaking study that finally figured it out, let me provide some context. Melanocytes are skin pigment cells. When our unprotected skin is exposed to the sun, it activates our melanocytes, which start releasing pigment to protect us from the UV rays. That’s what a tan is.

Where’s the harm in that? you may be wondering. UV light creates free radicals that can damage melanocytes and their DNA. If the DNA damage is extensive enough, the cells go rogue, basically, and become cancerous. That much we knew.

Here’s where the study, which was published in 2017 in the journal Cell Stem Cell, comes in.

Once a melanocyte cell’s damage crosses a certain threshold, each bit of sun exposure after that point can fuel the development of a tumor.

To recap, in healthy melanocytes, sun exposure will initiate a tan. But in damaged melanocytes – cells that have undergone a certain amount of genetic mutation – the same exposure has the potential to grow a tumor.

“If you had mutations that were sufficient for melanoma, everything would be fine until you went out and got a sunburn,” said Andrew White, a senior author of the study, said in a 2017 interview. “The stimuli that would normally just give you a tanning response could, in fact, start a melanoma instead.”

It’s not all concerning news. White and his fellow researchers also discovered a way to potentially prevent damaged melanocyte cells from turning into melanoma. They suspected a specific gene called Hgma2 is responsible for initiating the tanning response in melanocyte cells. To test their hypothesis, they took mice engineered with damaged melanocyte cells and exposed them to low levels of UV light after removing the Hgma2 gene from some of them.

The group that still had the gene went on to develop melanomas, but the other group, the one without the gene, did not. So, in the near future, targeting this gene could be a way of preventing melanoma from ever happening.

In the meantime, what can you do to protect yourself? What this study showed us is that skin cancer is essentially a two-factor process. So, even if you’ve damaged your melanocyte cells by neglecting your sunscreen routine, you can still stop damaged cells from developing into melanomas by being meticulous about protecting yourself from the sun. 

That means applying a broad-spectrum sunscreen with an SPF of at least 30 every day before your head out. And then again, every couple of hours. Also try to avoid the sun during peak hours (10 AM to 2 PM). And make a point of seeing a board-certified dermatologist for a comprehensive skin check at least once a year. Skin cancer, even melanoma, is almost always curable when it’s detected early on.