STUDY FINDS SMOKE CAUSES CELL DAMAGE.

Byline: David Stout The New York Times

A team of researchers says it has found a direct scientific link between smoking and lung cancer, a discovery that adds yet another piece to the already substantial evidence that tobacco smoking is a cause of cancer.

The findings, published today in the journal Science, report the first evidence from the cell biology level linking smoking to lung cancer. The scientists say a chemical found in cigarette smoke has been found to cause genetic damage in lung cells that is identical to the damage observed in many malignant tumors of the lung.

The findings reported today establish the long-missing link, in the opinion of experts in the field of cancer genetics, and also may play a role in pending litigation about smoking illnesses and passive smoking.

While many scientists have long been convinced by statistical studies and animal experiments that tobacco causes cancer, a statistical association was not in itself absolute proof.

This shortfall has allowed defenders of smoking to deny that cigarettes cause cancer, and scientists have not known the exact mechanism of causation that would put the matter beyond doubt.

``This paper absolutely pinpoints that mutations in lung cancer are caused by a carcinogen in cigarette smoke,'' said John Minna, a researcher at the University of Texas Southwestern Medical Center. ``It is the smoking gun that makes the connection.''

``It puts a very firm nail on this coffin,'' said Bert Vogelstein of the Johns Hopkins Oncology Center in Baltimore.

The Tobacco Institute, a trade group based in Washington, and the New York office of Philip Morris said Thursday that they were not prepared to comment on the Science article.

Tom Lauria, an institute spokesman, said the Tobacco Institute's position has been that ``the causal link remains to be established'' between smoking and lung cancer. He said the institute recognized that ``smoking has been shown to be an important risk factor in heart disease, lung cancer and emphysema.''

John Banzhaf, a professor of law at Georgetown University who is familiar with laws and lawsuits that deal with smoking said the new research would have profound consequences, both in the courtroom and in everyday life.

``This is very important in imposing liability on the cigarette industry and in protecting nonsmokers from secondhand smoke,'' said Banzhaf, who is executive director of ASH, for Action on Smoking and Health, a nonprofit anti-smoking group.

Banzhaf said the latest study would be a powerful weapon for eliminating smoking from those public places that still allow it. ``We're moving to ban smoking even in bars, the last bastion,'' he said.

And he predicted that the research's pinpointing of a specific mechanism for lung cancer would be a severe blow to the tobacco industry in court, where until recently it had been all but impervious to lawsuits from people claiming that they had become ill from smoking.

Scientists familiar with the work described in the Science article predicted that the techniques would have wide use in establishing links between other suspected carcinogens and specific types of cancer.

Minna, the University of Texas researcher, said the methods described in the article would become ``the DNA forensic pathology of the future.''

In the paper published today in Science, researchers from the University of Texas M.D. Anderson Cancer Center in Houston and the Beckman Research Institute of the City of Hope in Duarte studied the effects of a cigarette-smoke ingredient on a gene known as p53.

The gene is vital to the body's well-being because it acts to suppress the runaway growth of cells that lead to tumors.