Formula for lung cancer risk

How long and how much you smoked, and how long it’s been since the last puff, make a difference in the risk of getting lung cancer.

Scientists have come up with a formula that certain smokers and ex-smokers can use to calculate that risk – one that could help people decide if they really want a controversial test for lung cancer.

The formula, published in this week’s Journal of the National Cancer Institute, shows a wide variation in risk.

Consider a 51-year-old woman who smoked a pack a day since she was 22 until stopping nine years ago. The formula puts her chances of getting lung cancer in the next 10 years at less than one in 100.

Compare a 68-year-old man who smoked two packs a day since he was 18 and hasn’t yet quit. He has a one in seven chance of lung cancer by his 78th birthday if he keeps puffing. If he quit smoking today, the risk drops slightly, to one in nine.

The formula only works for certain people – those older than 50, who smoked at least half a pack a day for at least 25 years – because it’s based on a study that tracked cancer development in just those people.

Researchers from New York’s Memorial Sloan-Kettering Cancer Center created the formula and posted a version on the center’s web site on Tuesday.

The new formula will help doctors “be more specific now about who is at greatest risk,” said Dr. Tom Glynn of the American Cancer Society, who praised the research.

AP

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