June 07, 2015
Skin is the largest organ in the body and the most often abused. While many of us know the important keynotes of sun safety — don’t use tanning beds, get burned or forget to wear sunscreen — the mechanics of sun damage are overlooked.
On the surface, our skin turns red, blisters and burns, but we often fail to think about what’s happening beneath the surface and how it can increase cancer risks.
“Sun damage spans a large spectrum of possibility, and prolonged, unprotected sun exposure is never safe,” said Dr. Paul Michael, Oncologist at Southern Hills Hospital and Medical Center.
It takes years from initial skin damage to develop a melanoma. That means a couple bad sunburns from childhood can lead to melanoma as an adult.
What is a sunburn?
A sunburn is an acute response to sun damage over a 24-hour period. A tan is the damage caused by burning.
Types of rays
There are two types of ultraviolet rays, UVA and UVB. UVA rays contribute to the premature aging of skin, while UVB rays burn skin. “It was once thought that only the UVB rays caused cancer, but that’s been disproven — both UVA and UVB rays cause cancer. Isolating UVA rays, like many tanning beds do, isn’t safer,” Dr. Michael said.
How sun damage works
Ultraviolet light is a type of damaging radiation. “We know that too much radiation from x-rays or nuclear plants, for instance, harms the body. Ultraviolet radiation causes lasting and severe cellular damage,” Dr. Michael said.
Sun to cells:
When skin is exposed to excessive sunlight, radiation damages DNA in the skin cells. As a response, the body produces melanin, a pigment that’s meant to prevent further damage to the skin’s DNA and makes skin look tan.
Think about it like this...
UV rays fire millions of little arrows into the skin. When the DNA in each cell gets hit, the skin uses melanin as a shield to try to defend against more incoming arrows. Melanin shields the skin with its dark pigment. Because light is absorbed better by darker colors, the melanin tries to absorb the UV rays so the DNA in the skin cells doesn’t have to.
No tan is a safe tan:
Because melanin production is triggered by the first UV “arrow” to the cell’s DNA, there is no such thing as a safe tan. “People need to understand that any tan, no matter how dark or light, is the product of skin damage,” Dr. Michael said. Once DNA is damaged, it leaves the cell susceptible to cancerous mutations.
What about sunscreen?
Sunscreen is a great insurance policy, but it’s not supposed to be your only line of defense against UV rays. Everyone should wear sunscreen if they’re out in the sun at all, but they also need to cover up and seek shade. “Many people don’t use sunscreen correctly,” Dr. Michael said. “They don’t reapply often enough, they miss spots, stuff like that. Sunscreen always needs to be paired with safe sun practices.”
When you should see a doctor
“Any change of the skin, be it a new mole or a change in an existing mole, needs to be checked by a doctor,” Dr. Michael said. There also are “the ABCD’s” of changes to look for in existing moles:
Asymmetry: One half of the mole does not match the other half
Border: A change in the edges of the mole (i.e. it once was smooth and round; now it is ragged)
Color: A change in the color of the mole (i.e. it becomes darker or changes color in any way)
Diameter: An increase or change in the size of the mole
Types of Skin Cancer
- Melanoma is the most aggressive and deadly type of skin cancer. Melanoma develops when unrepaired DNA damage in skin cells triggers mutations that create tumors. Melanoma most often is caused by infrequent, but intense, UV exposure. “We usually see melanoma in people who aren’t spending every day in the sun but are subject to multiple sunburns throughout their lives,” Dr. Michael said. Melanoma is not the most common type of skin cancer but it is far and away the most deadly.
- Squamous Cell Carcinoma (SCC) is the second most common type of skin cancer. It can be fatal if it isn’t caught early. Unlike melanoma, SCC most often occurs in people who have daily, prolonged exposure to the sun.
- Basal Cell Carcinoma (BCC) is the most common type of skin cancer. It typically is localized and rarely spreads beyond the tumor site. It does not grow back once it’s removed.
- Actinic Keratosis is a precancerous change, often a precursor to squamous cell carcinoma.
- Lentigo Maligna is a precancerous mole, often a precursor to melanoma. It sometimes is referred to as pre-melanoma.