Most potentially deadly skin cancer cases begin as new moles or freckles.

Stopping melanoma from turning deadly means finding and removing the cancer early.

But this can be tricky since this cancer — the most dangerous form of skin cancer — can masquerade as a harmless mole or freckle until it spreads too far to be effectively treated.

A report published today sheds some light on when to get these kinds of spots checked by a doctor.

According to the new study published in the Journal of the American Academy of Dermatology, the majority of melanomas do not appear on existing moles, but show up as new marks on the body.

The study comes as melanoma rates have continued to increase in recent years.

The American Cancer Society estimates there will be 87,000 new melanoma diagnoses in 2017, and the cancer will lead to 9,700 deaths.

To find a way to help people with melanoma, researchers from the University of Campania and University of Modena and Reggio Emilia in Italy, along with other institutions, did a meta-analysis of data pulled from 38 studies that included information on a total of 20,000 cases of melanoma.

After reviewing these cases, researchers found that an estimated 71 percent of melanoma cancers arise “de novo,” or appear as new spots on the body, rather than originating in existing moles.

The other 29 percent arose in existing moles. The researchers also found that cancer in existing moles tended to be thinner, which indicates a patient has a higher chance of survival.

The researchers explained that these findings could help patients better identify the warning signs of early skin cancer.

“These results could indicate that patients who monitor their existing moles for suspicious changes could detect melanoma in its early stages, when it’s most treatable,” Dr. Caterina Longo, PhD, a study author and a dermatologist at the University of Modena and Reggio Emilia in Italy, said in a statement.

Dr. Michele Green, a dermatologist at Lenox Hill Hospital in New York, said she’s seen in her own work how often melanoma can appear harmless to the untrained eye.

“I found that in my practice for years… it’s been new moles,” she told Healthline.

Anecdotally, Green said, the melanoma she usually finds are small and dark. She said she’d heard from many patients that they had no idea that the mark was something to be concerned about.

Melanoma can, however, be different sizes and colors.

Dr. Barney Kenet, a New York-based dermatologist, said the findings are helpful, but shouldn’t drastically alter a person’s approach to skin care safety.

He recommended patients look for change overall, either in an existing mole or anything new on the skin.

“You see something changing, that’s a good time to go” [and] get checked, he said. “It can all be reduced to the word ‘change.’”

Additionally, he said it’s important to be familiar with your moles and freckles so that if a new spot pops up or something changes, you can get to the doctor more quickly.

Melanomas caught at the earliest stage have a virtual 100 percent cure rate, Kenet explained. The change of just a few millimeters in a melanoma can often mean the difference between life and death.

Kenet stresses that even if you see a suspicious mole or spot, you should not panic, but instead simply get it checked out.

We’re just trying to give the public relatively simple tools to know when to get to the dermatologist,” he said.

With many people heading out to enjoy some time in the sun this Labor Day weekend, Green has a few tips to ensure staying safe under the sun.

She tells her patients a handy way to remember to reapply sunscreen is to do this every time they have to use the bathroom.

Also, she says never forget your sunglasses and a hat.

“Try to cover up as much as you can — a hat and sunglasses — they’re really important,” she said.

Some patients even “have melanomas in their eyes.”

The American Academy of Dermatology also has a helpful way of remembering when to get a mole checked out.

You can identify if something seems wrong by adhering to the ABCDEs of melanoma.

A = Asymmetry means part of the mole looks different from the other half.

B = Border means the border is not a perfect circle and has irregular lines.

C = Color means part of the mole has an unusual color or different shades.

D = Diameter means that since melanomas are often greater than 6 millimeters in diameter at diagnosis, anything that size should be checked.

E = Evolution means that if the mole changes over time, it should be checked.