Cancer's secret a switch in gene

By SCOTT MacLEOD

Scientists have discovered a genetic switch that makes the deadliest skin cancers spread - a breakthrough which holds special promise for New Zealanders.

The findings have already prompted scientists to work on drugs they hope will block the spread of melanoma. This country has one of the highest rates of skin cancer in the world, with 250 deaths a year.

Scientists at the Wellcome Trust Sanger Institute in Cambridge, England, found a mutant gene called B-Raf in 70 per cent of malignant melanomas, the most lethal form of skin cancer.

One project leader, Professor Mike Stratton, said the gene turned on a cell's growth switch so it kept dividing.

"Because mutated B-Raf is stuck in the 'on' position, we've already started searching for drugs that will switch it off," he told Nature magazine.

The bad news is that it could take 15 years to develop a drug that will tackle the gene.

Cancer Society medical director Peter Dady greeted the findings as a big step on the road to beating melanoma.

"Fifteen years is not a long time in drug-development terms," he said.

The director of the cancer genetics laboratory at Otago University, Tony Reeve, said the findings sounded like good, solid science.

He said genetic research was helping to break cancers into sub-categories. It was likely that cures that would work on some forms of melanoma, for example, might not work on other forms.

"It looks like they have struck gold on this one," Professor Reeve said, "but it's early days for this technology."

Melanoma kills more than 40,000 people a year worldwide. In New Zealand, the last available figures are from 1998. That year, 143 males and 105 females died from skin cancer and 1500 people were registered as having some form of the disease.

About 80 per cent of the deaths were caused by melanoma, which is relatively easy to treat if caught early.

Cancer Society spokeswoman Liz Price said the best cure for melanoma was prevention. The biggest risk factor was ultraviolet light.

The British breakthrough is one of the most important to come from the Cancer Genome Project.

The scientists are matching 48 types of cancer with the 30,000 genes in the human genome.

nzherald.co.nz/health