SEATTLE (AP) _ Lung cancer became an epidemic in the United States about 20 years after the invention of the machine to mass-produce cigarettes, a doctor testified Thursday.

Dr. David Burns, a professor at the University of California's medical school, was the first witness to testify in Washington state's lawsuit against seven tobacco companies.

The lawsuit, like others filed against the industry, accuses tobacco companies of conspiring to violate antitrust and consumer-protection laws, suppressing health research and manipulating nicotine levels.

Prosecutors seek as much as $2.2 billion that the state allegedly spent treating smokers.

Burns said that although the death rate for most types of cancer has decreased or stabilized since 1930, the rate of deaths from lung cancer _ which was an extremely rare cancer as recently as 1900 _ skyrocketed.

The tobacco industry has long taken the position that there was not enough scientific evidence to say smoking caused lung cancer. Burns said there was plenty of evidence.

Defendants in the case are American Tobacco; Brown & Williamson Tobacco Corp., Lorillard Tobacco Co., Philip Morris, R.J. Reynolds Tobacco Co., United States Tobacco Co. and B.A.T. Industries P.L.C., and related organizations including public-relations firm Hill & Knowlton, The Council for Tobacco Research-USA Inc., Smokeless Tobacco Council and the Tobacco Institute.