Gene clue for early signs of melanoma

Researchers have identified a gene that causes benign moles on the skin to become cancerous, a finding that could allow doctors to treat more effectively patients with early stages of melanoma.

A team of scientists led by Dr Rhoda Alani of Johns Hopkins University, Baltimore, found a gene known as Id1 that causes cancer cells to grow in melanoma.

Id1 blocks a tumour suppressor gene that usually keeps precancerous moles from progressing to melanoma or skin cancer.

The study found that high levels of the Id1 protein were evident only in the first stages of melanoma, when the disease was on the surface of skin.

The American Cancer Society says patients with a melanoma that has not spread below the skin have a survival rate of 97 per cent beyond five years.

But as the tumour begins to grow, the survival rate falls to 50 per cent if it has reached the lymph nodes below the skin and 20 per cent if it has spread to other organs.

"If this actually works out that the protein is activated on a larger scale, it will be very useful for the diagnosis of this disease," Dr Alani said.

"If you make the diagnosis early, you can essentially cure a patient of this disease."

Experts say a person's risk of melanoma is influenced by family history, exposure to the sun, the number of moles and skin sensitivity.

Researchers studied Id1 protein levels in 21 human tissue samples including precancerous moles and various stages of melanoma.

Writing in the Cancer Research journal, they said diagnostic tools could be designed to monitor Id1 because it was activated only in the early stages of melanoma.

Id1 might also cause mutations to occur in the cancer cells, making the suppressor gene damaged beyond repair. As the cancer grew, Id1 levels fell because it was no longer needed to block the suppressor gene.

Dr Alani wanted a study of several hundred patients to verify the Id1 role before seeking a method to test for it.

"Developing a diagnostic tool is easy, but we want to devise one that is rapid and easily done," she said.

This was important because the diagnosis of melanoma was difficult and treatment varied based on the degree to which it had progressed.

Dr Alani said doctors often have had difficulty determining if a mole was cancerous.

By developing a test to detect Id1, doctors would be able to better treat patients with the disease.

Melanoma tumours spread quickly, and the best treatment is to surgically remove the cancer because patients normally do not respond well to chemotherapy and radiation.

The cancer society estimated there would be 51,400 new cases of melanoma in the US this year. About 7800 people would die of it, making it the most deadly type of skin cancer.

It is the sixth most common form of cancer in US men and seventh in women.

- REUTERS