What Causes Skin Cancer?

By: Amber Robbins, MD, FAAD

Our patients often ask what caused their skin cancer, and the answer is easy - in almost all cases skin cancer is caused by radiation!  But patients aren’t usually hanging out by nuclear power stations or watching atom bomb tests, they are getting radiation every single day - from the sun.

The sun is basically an enormous nuclear reactor that provides our planet with just the right amount of light and heat, but with a healthy side serving of radiation!  The sun makes a few types of radiation, but the type that causes skin cancer is Ultraviolet (UV) radiation.  These are waves that travel along with sunlight and are invisible - they can get through clouds and even clothing. Tanning beds deliver a similar type of UV, UV-A, which mimics harmful rays from the sun.  

When UV radiation waves make it through the top layer of our skin, they hit the DNA - the important code that tells our cells how to behave - of our skin cells.  When radiation waves hit the DNA they damage it in specific ways. The cells we are made of are amazing and have ways to repair this DNA damage, but can only handle so much before they are overwhelmed.  Therefore, think of a sunburn as a radiation burn that has caused an extreme amount of damage to the skin, overwhelming the cells’ repair system. 

Once enough damage accumulates, the skin cell can tip over into a precancerous or cancerous state, and they will begin to replicate without stopping.  The cancer then will continue to grow and can spread. 

Of course we need to be outside in the sun to be healthy, happy humans, but every dermatologist will tell you that the more you protect your skin from UV radiation, the longer it will last and the healthier it will be. You’ll also have a lower risk of skin cancer.  Sunscreen with SPF30 or greater applied correctly, UPF clothing, hats and shade are your best bets for protection.