The incidence of lung cancer skyrocketed after the use of cigarettes increased during the two world wars, a doctor testified in the trial of Washington state's lawsuit against the tobacco industry.

Dr. David Burns, a professor at the University of California's medical school, said Thursday that cigarette smoking was uncommon until the invention of a machine to mass-produce cigarettes in 1913.Twenty years later, lung cancer began to increase dramatically, even though the death rate for most other types of cancer has decreased or stabilized since 1930, he said.

Burns is to resume testifying next week. Court was in recess today.

The state is seeking $2.2 billion in reimbursement for the cost of treating sick smokers. 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.

Burns, who has been involved in the preparation of more than a dozen surgeon general's reports on tobacco since 1975, said there was evidence of more than just an association between smoking and diseases like lung cancer.

"Absolutely, there is no question in my mind that smoking causes diseases," Burns said. "The more you smoke, the longer you smoke, the more you're at risk of developing lung cancer."