Most melanomas come from brand-new moles

You’re probably aware by now that you should have regular skin checks with your dermatologist to try to detect any abnormal-looking moles that could be a sign of melanoma, the most deadly form of skin cancer. And, given that you know your body best, you’re also probably aware that you should be checking your skin yourself on the regular.

Of course, it can be hard to find the time between work, life in general, and just plain forgetting. Now new research shows just how vital it is for you to be on top of any new moles on your skin — they’re more likely to be melanoma.

That’s the main takeaway from a new meta-analysis published in the Journal of the American Academy of Dermatology. For the study, researchers reviewed 38 published studies on 20,126 melanomas and found that less than one-third of melanomas arose from an existing mole. Instead, the vast majority (71 percent) showed up as new moles on a person’s skin. Melanomas that formed from existing moles were also thinner than other melanomas, suggesting that people who had these moles had a better prognosis that those with melanomas on new moles.

More than 87,100 new melanoma cases will be diagnosed in the U.S. in 2017, and about 9,730 people are expected to die of the disease this year, according to the American Cancer Society. Genetics and skin type play a role in the development of the disease (people with lighter skin are more likely to develop melanoma than those with darker skin), but sun exposure is a big component as well.

Gary Goldenberg, MD, assistant clinical professor of dermatology at the Icahn School of Medicine at Mount Sinai Hospital in New York City, tells Yahoo Beauty that he’s not surprised by the data. “We’ve long known that the majority of melanomas are melanoma from the start — meaning that they are new lesions,” he says. That’s why he says it’s so important to be aware of your body and any skin changes, and to make sure new spots don’t have the ABCDE criteria for melanoma. Look for asymmetry, an uneven border, a variety of colors, a diameter larger than the size of a pencil eraser, and a mole that is evolving in size. ( has photos and more information.)

The American Academy of Dermatology encourages people to get their moles checked regularly by a dermatologist but also recommends that people do regular skin self-exams, and ask a friend or partner to help them check areas that are hard to see, like their back. “Any new dark spot on the skin should be evaluated by a dermatologist,” Joshua Zeichner, MD, a dermatologist in New York City, tells Yahoo Beauty. “Our bodies typically stop producing new moles after the age of 30, so if you develop a new spot, the reason may be that it is cancerous.”

Of course, these new findings don’t mean that you should write off old moles when doing a skin check. “Any cell in the body can mutate into cancer,” Cynthia Bailey, MD, a diplomate of the American Board of Dermatology and president and CEO of Advanced Skin Care and Dermatology, Inc., tells Yahoo Beauty. Bailey does mole-mapping photos, so that she can compare her patients’ current skin with the way it looked in the past and keep an eye on evolving moles. But not every doctor does this. If you have a mole that you’re unsure about, get it checked out and take photos yourself if your doctor doesn’t — it could come in handy in the future.

But make sure to get your skin checked by a dermatologist every year, even if you’re doing your own regular skin exams, Goldenberg says. It could save your life.

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