How Does Sunlight Cause Skin Cancer?

I think by now many people know that skin cancer is a major problem (it is the most common form of cancer in the United States) and that too much sun exposure can lead to skin cancer. But have you ever wondered how sunlight leads to skin cancer? Let's dive into the science!

Our Sun bathes the Earth with electromagnetic radiation, which provides our planet with warmth and the energy needed for life. This radiation comes in a spectrum of wavelengths, including infrared, visible, and ultraviolet. Our atmosphere is able to filter out some, but not all, UV light; the remainder reaches the Earth's surface. When UV light enters the skin, it damages the DNA of the cells. DNA serves as the instruction manual for cells; when the cell accumulates too much damage it can become cancerous. Cancer cells grow uncontrollably, damage their host tissue, and can eventually metastasize to other parts of the body.

Here is an interesting aside about tanning. When the DNA of melanocytes, which are one type of skin cell, become damaged by UV radiation, the melanocytes produces melanin. Melanin acts as an intracellular umbrella to shield cells from additional DNA damage, and it makes our skin look tanner. But notice that cancerous damage is what triggers the tanning response: there is no way to get a "healthy" tan!!  

The best way to minimize your risk of skin cancer is to shield your skin from ultraviolet radiation. Fortunately, we have many excellent ways to do this: sunscreen, sun protective clothing, seeking shade, and avoiding prolonged sun exposure between 10 AM and 2 PM. I am not recommending that you should hide in a cave: go enjoy the sun and the outdoors! Just be smart and remember to protect yourself.