Here is some good news for smokers. A new study suggests exercise can help reduce, at least a bit, their lung cancer risk. That’s lung cancer as in the nation’s leading cancer killer.

A study of more than 36,000 women found that a physically active smoker had a 35 percent lower of lung cancer than a sedentary smoker. The results are reported in the the current issue of the journal Cancer Epidemiology Biomarkers & Prevention.

Dr. Kathryn Schmitz, the study’s lead author, cautioned against reading the results as a license to light up and inhale. “The most important thing a smoker can do to reduce risk is to quit smoking. That said, exercise and being active can offer a marginal change in risk,” she explained.

She noted that smokers are 10 to 11 times more likely to develop lung cancer than non-smokers.

For now, it’s not clear how exercise lowers lung cancer risk. Investigators said it might lead to better lung function, which would cut exposure to the cancer-causing particles and substances contained in smoke. Training might also cut cancer risk by tuning up a person’s disease-fighting immune system and taming inflammation.

The results came from the Iowa Women’s Health Study, a five-year study begun in 1986. Volunteers were ages 55 through 69 when the project began. Schmitz is an assistant professor at the University of Pennsylvania. The work also involved researchers from the University of Minnesota.