Gene test 'aids' skin cancer detection

Melanoma is caused by too much exposure to the sun

Doctors may be able to tell if a suspect skin mole is turning cancerous with a new genetic test.

The test could detect malignant melanoma, the most dangerous form of skin cancer, of which there are approximately 5,000 cases in the UK every year.

People with large numbers of moles, or nevi, are at an increased risk of developing melanoma, but it can be hard for doctors to spot the difference between an early-stage cancer and a benign mole.

If the cancers are spotted early, there is a much better chance of a complete cure, as cancers left too long can spread to other parts of the body.

The test looks for differences in the cell chromosomes - tiny parts of the cell which carry instructions on how it should work.

These differences mean that a melanoma cancer cell lives too long and divides uncontrollably - forming the tumour.

The test, developed at the University of California in San Francisco, stains the chromosomes in a suspicious mole with fluorescent dye and compared them to normal skin cell chromosomes.

'Simple test possible'

Professor Philip LeBoit, a professor of pathology at the university, said that a simple test should now be possible.

"Now we have a common set of abnormalities for melanoma. And most tumours have two, three or four of them."

A UK experts on screening, Dr Douglas Easton, from the Cancer Research Campaign's genetic epidemiology laboratory in Cambridge, said that the test would only be used on patients considered to be at high risk, rather than used to screen large sections of the population.

"It's not the same as breast cancer or colon cancer, where you can carry out a further investigation if you get a positive result.

"With this test, all you could do is watch and wait."

Melanomas make up only a small proportion of the skin cancers in the UK - people with fair skin who are exposed to strong sunlight regularly are at higher risk.

Most other skin cancers mainly affect the elderly, and can be easily treated.

Melanoma, because of its tendency to spread if left too long, may require extra treatment such as chemotherapy.