Risk of lung cancer not proven to start at 5 years
WHEELING, W.Va. (AP) -- There is no proof that people who smoked a pack of cigarettes a day for five years and then quit are at a statistically significant, higher risk of developing lung cancer, but a health expert who testified against the tobacco indus
Few scientific studies have ever looked at short-term smokers, and the ones that have analyzed long-term smokers found "biologically meaningful" risk after 20 pack years, said Dr. David Burns, a professor of pulmonary medicine at the University of California-San Diego.
A pack year is defined as the equivalent of a pack a day for a year. Smokers can accumulate pack years faster if they smoke more than a pack a day.
Burns is an important witness in the class-action lawsuit that some 250,000 West Virginia smokers have filed against R.J. Reynolds, Philip Morris, Lorillard and Brown and Williamson. He helped develop the proposed medical monitoring program the lawsuit seeks for symptom-free smokers who have at least a five pack-year history.
The smokers say they have been exposed to a defective product and now deserve a screening program that could lead to lifesaving early detection of lung cancer, emphysema and chronic obstructive lung disorders.
Creating that program could cost the tobacco industry hundreds of millions of dollars, and cigarette makers argue the tests the smokers want are still experimental and unproven in reducing mortality.
When initially questioned, Burns said a five pack-year history -- or the consumption of 36,500 cigarettes -- is enough to qualify as significant exposure to a known hazardous substance. That's among the half-dozen points the smokers must prove to prevail.
"The more you smoke, the more likely you are -- other things being equal -- to develop lung cancer," Burns said.
However, under cross-examination that will continue Thursday, Burns conceded that no studies have been published to define where a smoker's risk of developing lung cancer actually begins. A few were conducted, he said, but the results were inconclusive.
Burns, who has helped write, edit or review every U.S. surgeon general's report since 1975, teaches pulmonary medicine, studies tobacco and health issues, and routinely testifies against the industry.
R.J. Reynolds attorney Jeff Furr painted Burns as a longtime industry foe with both a financial and political agenda. For his involvement in the case this week, Burns will make about $20,000.
He also has drafted medical monitoring programs for litigation against the tobacco industry six times, including for a pending case in Louisiana. This is the first plan to make it to trial.
"It would be useful public policy to have the kind of remedy this case proposes," Burns said.
While quitting is always beneficial and can slow or stop the progression of disease, it does nothing to help detect illness, he said. And the risks to even longtime ex-smokers never fully disappear.
Within five years of quitting, a smoker's risk of developing lung cancer is cut by 30 percent. After 10 smoke-free years, the risk is cut in half. If a person remains a nonsmoker for 15 years, their risk is cut by nearly 80 percent.
"But it never goes back to the level of someone who has never smoked," Burns said.
About half of the people being diagnosed with lung cancer in the United States today are ex-smokers, he said.
"In a sense, it's like a pickle," Burns said. "You can make a cucumber into a pickle, but you can never make it go the other way."
The "relative risk," meaning the risk compared to people who continue to smoke, will decline, Burns said. "But the absolute risk is constant."
Medical monitoring in this case means lung-function tests for all symptom-free smokers at age 40, with a second test at age 45 and tests every two years after that.
Starting at age 50, healthy smokers also would get spiral computed tomography scans, or CT scans, which generate three-dimensional images of organs and can identify tumors earlier than traditional chest X-rays.
"There's no doubt in my mind that these procedures can early detect lung disease and chronic obstructive pulmonary disease," Burns said.
The trial will enter its 11th day Thursday with all nine remaining jurors, including one who was released earlier this week to deal with a family problem that he has since resolved.