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• Smoking shaves more than 10 years off the average life span, but quitting at any age buys time. Quitting by age 40 avoids nearly all the excess risk of death from smoking. Men and women who quit when they were 25 to 34 years old gained 10 years; stopping between ages 35 and 44 gained 9 years; between ages 45 and 54, six years; between ages 55 and 64, four years.

• The risk of dying from other lung diseases such as emphysema and chronic bronchitis is rising in men and women, and the rise in men is a surprise because their lung cancer risk leveled off in 1980s.

Changes in cigarettes since the 1960s are a “plausible explanation” for the rise in noncancer lung deaths, researchers write. Most smokers switched to cigarettes that were lower in tar and nicotine as measured by tests with machines, “but smokers inhaled more deeply to get the nicotine they were used to,” Dr. Thun said. Deeper inhalation is consistent with the kind of lung damage seen in the illnesses that are rising, he said.

Scientists have made scant progress against lung cancer compared with other forms of the disease, and it remains the leading cause of cancer deaths worldwide. More than 160,000 people die of it in the U.S. each year.

The federal government, the Canadian Institutes of Health Research, the Bill and Melinda Gates Foundation, the cancer society and several universities paid for the new studies. Dr. Thun testified against tobacco companies in class-action lawsuits challenging the supposed benefits of cigarettes with reduced tar and nicotine, but he donated his payment to the cancer society.

Smoking needs more attention as a health hazard, Dr. Steven A. Schroeder of the University of California at San Francisco wrote in a commentary in the journal.

“More women die of lung cancer than of breast cancer. But there is no ‘race for the cure’ for lung cancer, no brown ribbon” or high-profile advocacy groups for lung cancer, he wrote.

Kathy DeJoseph, 62, of suburban Atlanta finally quit smoking after 40 years — to qualify for lung cancer surgery last year.

“I tried everything that came along. I just never could do it,” even while having chemotherapy, she said.

It’s a powerful addiction, she said. “I still every day have to resist wanting to go buy a pack.”