As the body's largest organ, skin is hard to ignore.

But every time you go outside without sunscreen or other protection from the sun's harmful rays, doctors say, you're doing just that.

"Melanoma is one of the deadliest forms of cancer, but it's also one of the most preventable," says Dr. Kent Aftergut, a dermatologist. "It's really a shame when anyone dies from skin cancer."

That's why the advent of summer is prime time for reinforcing good advice: Go to the doctor for a yearly skin checkup, make monthly self-examinations of your body, wear protective clothing and slather on sunscreen if spending any time outside.

Melanoma, a cancer often marked by irregular spots on the skin that can spread if left untreated, kills close to 8,000 people each year, although it is considered preventable and curable if caught early.

Although most people diagnosed with melanoma are white men over the age of 50, skin cancer is showing up more and more among women and young people, according to the Skin Cancer Foundation.

In the past three decades, skin cancer rates have tripled in women under 40, and cases of pediatric melanoma have doubled in the last 20 years.

Those numbers are why Tracy and Dan Olsen took their two teenage daughters to a free skin cancer screening last month.

"We're of Norwegian descent, so getting checked is just the smart thing to do," Tracy Olsen said.

People with fair skin, blond or light-colored hair and who freckle or burn easily are most at risk for skin cancer. Since 14-year-old Jackie Olsen fits that description, dermatologist Rebecca Euwer gave the teenager a thorough examination on her face, chest, arms, legs and elsewhere.

Skin cancers often arise as a new or changing mole, so Euwer cautioned the Olsens to follow the "ABCDs of melanoma" when making examinations of their skin.

• Asymmetry: Melanomas often have sides that do not match

• Border irregularity: Unhealthy moles might have ragged or notched edges

• Color: Healthy moles will usually have a uniform color while a melanoma might have spots of black, red, blue and other colors

• Diameter: Melanomas often are wider than inch.

Cory Spillman says he hadn't noticed anything wrong with his skin when he went to the dermatologist two years ago. He had just passed his 30th birthday, so he decided to go in for a checkup.

As a golfer and all-around lover of the outdoors, he'd spent much of his youth under sunny skies without paying much attention to his complexion.

"I wore sunscreen when I thought about it and didn't when I didn't think about it," Spillman says.

When the doctor identified an odd spot on his chest during the visit, Spillman tried to persuade him not to biopsy it.

"I tried to talk him out of it because I didn't want him to do it," Spillman says. "It hurt."

But the doctor took the sample anyway, and he called Spillman a week later with bad news.

The spot was melanoma, and they needed to schedule surgery to remove the cancer immediately before it could spread to his lymph nodes, lungs or other places where it can be very difficult to treat.

"When he told me about it, I just couldn't believe it. I said, 'I'm much too young for this. This can't be right,"' he says.

Now Spillman is cancer-free, although he's got a 3-inch scar on his chest as a reminder of the scare. He's become an outspoken advocate for long-sleeve shirts, pants, hats and sunscreen.

He still spends a lot of time under the sun at neighborhood events — he's mayor pro tem of Cedar Hill, Texas — but he says he always has sunscreen in his pocket.

He also has it at his desk, in his car and in his wife's car.

"I'm so lucky that we caught mine early, before it could spread," says Spillman, who visits the dermatologist every two months for checkups. "Now I want to let everyone know that there are things you can do to change your risk of skin cancer without changing your lifestyle."

Because one blistering sunburn in childhood can double a person's chances of developing skin cancer later, experts encourage parents to practice good sun protection with their children from infancy.

Children under 6 months should be kept out of the sun because their skin can be too sensitive for sunscreen.

"The protection must start in young people and children early, because that's where a lot of damage is done," Aftergut says.

Tracy Olsen says she believes the lessons she's teaching her teenage daughters about the importance of checkups and sun protection will stay with them into adulthood.

"You should see our collection of sunscreens," says 16-year-old Marcy Olsen. "I gave up on any chance of a tan long ago."