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Study: Smoking can trigger permanent increase in lung-cancer risk

August 22, 1997

PITTSBURGH (AP) _ Toni Baran gave up cigarettes in 1982. Still, to her it’s no wonder that 30 years of smoking three packs a day probably did irreparable damage to her lungs.

A new study suggests long-term smoking throws a biological switch, encouraging both healthy and mutated lung cells to multiply _ permanently increasing the odds of developing cancer.

That’s not news to Mrs. Baran, who now teaches stop-smoking classes in Honolulu.

``I’m not plastic, so where’s the surprise?″ she said. ``You can’t do that kind of behavior for that long and be surprised that there’s a price to pay for it.″

The University of Pittsburgh study, released Thursday and published in the August issue of the Journal of Respiratory and Critical Care Medicine, looked at lab-grown lung cells from 37 non-smokers, light smokers and heavy smokers.

``Once this switch is turned on, it appears to be permanent, which may explain in part why long-term ex-smokers who have not had a cigarette in over 25 years are still at high risk for getting lung cancer,″ said Dr. Jill Siegfried, who directed the study.

Heavy smokers were defined as those who had more than 25 ``pack-years,″ smoking the equivalent of one pack a day for 25 years or two packs a day for 12 1/2 years.

The researchers found an abnormal protein on the surface of lung cells from the heavy smokers. The protein, gastrin-releasing peptide receptor, attracts a type of hormone that stimulates cells to divide.

``The more cell growth you have, the greater the chance that one of those mutated cells will be the one that grows,″ Siegfried said.

The harmful protein was not present in the light smokers, but Siegfried said a larger survey would be needed to determine when irreversible damage sets in.

Other researchers said Siegfried’s findings were significant.

Dr. Vincent Miller, a lung-cancer researcher at Memorial Sloan-Kettering Cancer Institute in New York, said the study explains one reason why ex-smokers are twice as likely to develop lung cancer as those who have never smoked.

Many smokers mistakenly believe that when they stop, their lungs will eventually become healthy again, said Dr. Frank Cuttitta of the National Cancer Institute. He said this study shows why that doesn’t happen.

But Eric Hunsaker of Pittsburgh, who has smoked cigarettes for nine years, said the knowledge that he may be on the way to damaging his lungs permanently would not make him quit.

``I don’t think any study will make you say, `Gee, I’m going to stop smoking,‴ Hunsaker said.

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