The newly isolated gene for "elephant man's disease" appears to be a switch that can turn on cancer, a discovery that could lead to new treatments for cancer, researchers report today in the scientific journal Cell.

"The payoff here is going to be that we may come up with a treatment for brain tumors," said Allan Rubenstein, medical director of the National Neurofibromatosis Foundation in New York. Elephant man's disease is properly known as neurofibromatosis, or NF.

"Research is going to explode in a disease which a couple of years ago was an obscure phenomenon which practically the whole scientific world ignored," Rubenstein said.

"It's the kind of understanding we hoped discovery of the gene would lead to," said the author of the new finding, Raymond L. White of the University of Utah. "I expect it to make a fundamental contribution to our understanding of cancer genetics."

Researchers cautioned that treatments will be years away.

White's report concludes that the neurofibromatosis gene is one of the family of "GAP genes" that may operate as anti-cancer genes.

That is, when the genes are normal, they keep cancer growth switched off. When they are defective, they allow cancer tumors to grow. These so-called tumor-suppressor genes have been found to be among the causes of lung cancer, breast cancer and colon cancer.

White said his findings suggest that neurofibromatosis tumors, which are not cancerous, may be an intermediate stage between normal tissue and cancer.

Similar discoveries have been made in colon cancer, where White and other researchers have shown that benign polyps have some, but not all, of the genetic changes required to cause colon cancer.

Neurofibromatosis afflicts 100,000 Americans whose symptoms can include learning disabilities and crippling, non-cancerous tumors all over their bodies. Until now, researchers have had no clue to its cause.

Four weeks ago, White and Francis Collins of the University of Michigan reported that they had each independently discovered the neurofibromatosis gene.

That discovery opened the door to further studies to determine precisely what goes wrong in NF, and how it might be fixed. The latest findings are an important step in that direction, researchers said.

"The potential to start to design therapies is now a couple of years closer than it could have been otherwise," Collins said.