Earlier research has found that those who have never smoked are more likely to survive than smokers, but up until know it wasn’€™t clear whether smokers can improve their odds by quitting.

“The findings do suggest there is some benefit to quitting smoking,” said one of the authors, Amy Ferketich of Ohio State University College of Public Health in Columbus, United States.

The research revealed that older smokers who quit, or people who only quit once they were diagnosed with earlier stages of lung cancer, did not have an advantage over smokers.

The researchers collected data from the medical records of 4 200 lung cancer patients. They found that the patients who never smoked were more likely to survive less advanced cancers than were former or current smokers.

In smokers with stage 1 or 2 lung cancer, 72 percent survived at least two years, compared to 93 percent of never-smokers and 76 percent of people who’d kicked the habit a year or more before diagnosis.

Only 15 percent of smokers with stage 4 disease survived two years, while 40 percent of never-smokers and 20 percent of former smokers did.

For advanced cancers, people under 85 who had stopped smoking more than a year before their diagnosis survived longer than smokers.

“In general, never smokers are healthier individuals, so they tend to, in a lot of trials, have better outcomes with disease than people who continue to smoke,” she said. “Just the continued exposure to tobacco might make the disease progress more quickly in smokers compared to never-smokers who don’t have that exposure.”

Ferketich said it’s also possible that smoking could influence the biology of the cancer, and perhaps smokers get tumours that never-smokers are less likely to develop.

Source: Reuters Health