Health

Melanoma risk estimated from fast mole counts

Family doctors could count moles on the arm to estimate a patient's risk of melanoma, a British study suggests.
Family doctors could count moles on the arm to estimate a patient's risk of melanoma, a British study suggests 1:38

Family doctors could count moles on the arm to estimate a patient's risk of melanoma, a British study suggests.

Mole counts are an important marker of risk for skin cancer and having more than 100 on the body increases the risk of developing melanoma.

Melanoma can develop from abnormal moles. (CBC)

Melanoma can develop from abnormal moles but it's estimated between 20 per cent to 40 per cent of melanoma arises from a pre-existing mole, researchers say.

In Monday's online issue of the British Journal of Dermatology, researchers studied a group of more than 3,600 female twins over eight years. Specially trained nurses gathered data on skin type, freckles and moles on 17 body sites.

Then the study was repeated on about 400 Caucasian men and women with an average age of 45.

"If you have more than seven moles on your arm, you have nearly 10 times the risk of having nearly 50 moles," on your body, said study author Dr. Veronique Bateille, a dermatologist at King's College London. "If you have more than 10 or 11 on your arm, you have ten times the risk of having more than 100 moles."

Having more than 100 moles is a strong predictor of risk for melanoma.

The right arm above the elbow was also predictive of the total number of moles or "naevi" the researchers said.

 "This fast clinical evaluation should be used for a quick estimation of melanoma risk in general practices," the study's authors said.

Dr. Sandy Skotnicki is a dermatologist at St. Michael's Hospital in Toronto. She called mole counts on the arm a barometer or tool for physicians to assess how many moles there on the body.

But she didn't recommend patients try it.

"It's hard for patients necessarily to tell the difference between a mole and a freckle or a sunspot," Skotnicki said. "We don't want to incite panic."

Instead, Skotnicki suggested people should be aware of their moles and other risk factors, such as:

  • Fair skin.
  • Fair eyes.
  • A history of blistering sunburns, which increases your risk of developing melanoma by 50 per cent.
  • Family history.

If someone is concerned, they should see a family doctor for a screening.

Cancer specialists say it's also important for people to be aware of what's normal for their skin and to look for changes in the size, shape, colour or feel of a mole everywhere on the body.

Each year, approximately 5,000 Canadians are diagnosed with melanoma, the deadliest form of skin cancer, leading to 1,500 deaths. The Canadian Cancer Society expects more than 80,000 skin cancer cases in Canada this year. 

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