Sure, you know sunburns are bad for you and raise your skin cancer risk. That’s why you wear sunscreen. And you know to get any suspicious-looking moles checked by a doctor. But what you don’t know about skin cancer and sun protection may surprise you — and get you in trouble that’s more than skin-deep.

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1. Skin cancer is an older-people problem.

Totally false, says Elizabeth Hale, MD, a Manhattan dermatologist. Younger people can and do get all types of skin cancer, including basal cell, squamous cell and the more deadly melanoma. In fact, melanoma rates have been increasing rapidly among younger people.

"It's the leading cause of cancer-related death in young women," Hale says. According to the Melanoma Research Foundation, melanoma is the number one cause of cancer-related death in women 25 to 30 and the second leading cause of cancer death in women 30 to 35. Rates of melanoma have been rising among young men, as well.

This year, about 74,000 new cases of melanoma will be diagnosed in the United States, according to estimates from the American Cancer Society. More than 3.5 million cases of squamous and basal cell cancers are diagnosed annually.

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2. If I've had a mole forever, it’s fine.

Only partially true, Hale says. "It's true that most moles you have had since childhood won't become cancerous, but they can."

Typically, melanoma occurs from a new mole or one that has changed over time. If you notice any changes in a mole’s color, shape or size, or if it’s itching, painful or bleeding, see your dermatologist right away.melanoma melanoma (Photo: Australis Photography/Shutterstock)

Melanoma moles can have unique characteristics, such as being very large or having irregular borders. It can help to check out pictures of moles.

Having a lot of moles increases your risk of melanoma, Hale says.

3. Skin cancer takes a long time to grow. I'll get this funny spot checked out later.

''Non-melanoma skin cancers, basal cell and squamous, do grow more slowly," Hale says. "But melanomas can progress quite rapidly."

If you suspect any skin cancer, don’t delay seeing a dermatologist. Whatever else that’s on your schedule isn’t as important.

4. I haven't had a bad sunburn since I was a kid. I have nothing to worry about.

One blistering sunburn at a young age is enough to significantly boost your risk of skin cancer, Hale and other experts say. It can more than double your chance of developing melanoma later in life, according to the Melanoma Research Foundation.

5. If I had skin cancer, I would notice it.

Think again. Melanoma can develop in many more places than just exposed skin, according to the Melanoma Research Foundation. It can affect the eyes, scalp, mouth, feet and nails. It can even show up in between your toes, on the sole of your foot, behind your ears or even around your genitals. Non-melanoma cancers can pop up in hard to see places, like your back and the back of your neck.

More than one hair stylist and barber has been credited with getting a customer to the dermatologist on time.

Monthly skin self-checks are crucial, Hale says. "It's also important for people to see a dermatologist once a year for a professional skin exam."

6. I don't need a hat if I have sunscreen on my face.

"The top of the head, especially in those who have lost their hair, is very high risk [mainly for squamous cells cancers]," Hale says. "It's exposed every day."

So, yes, you do need a hat.

7. I put on sunscreen every morning, so I'm good to go.

Not reapplying sunscreen often enough is a big mistake, according to the Skin Cancer Foundation. Many people don't apply enough to begin with, either. You should apply an ounce, or about two tablespoons, of sunscreen everywhere that's exposed a half hour before going outside.

Reapply every two hours or right after you sweat a lot or go swimming.

If your skin is sensitive, choose fragrance-free sunscreens and opt for physical sunscreens (with zinc oxide or titanium dioxide) instead of chemical sunscreens, advises Rajani Katta, MD, a Baylor College of Medicine dermatologist.

8. The damage is done. I may as well forget sunscreen.

Bad idea, Hales says. "Really only about 25 percent of our lifetime sun exposure has occurred by adulthood," she says. And all that ongoing sun exposure during adulthood can have a cumulative effect, boosting your skin cancer risk.

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9. My dark skin protects me.

Not true. People of all ethnicities and skin colors can and do get melanomas and other skin cancers.

"When African-Americans get melanoma, they are often diagnosed at a much later stage," Hale says. The possibility of skin cancer may not occur to them, or to their doctors. Researchers have found their tumors tend to be more aggressive, as well.

10. I use a sunless tanner, so that will keep me from burning — and cancer.

''Sunless tanning is a much safer option for people who prefer to look tan," Hale says. She applauds the recent trend to sunless tanning over outdoor exposure or tanning beds.

However, Hale says, you still need to use sunscreen and follow other sun-safe habits, such as wearing long sleeves, staying out of the most intense sun at midday when possible and wearing long sleeves and pants if you can. 

Kathleen Doheny is a Los Angeles journalist specializing in health, behavior and fitness topics.