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WASHINGTON - Up to 20 per cent of women who develop lung cancer have never smoked and researchers think secondhand smoke may be to blame.
A survey of a million people in the United States and Sweden shows that just 8 per cent of men who get lung cancer are nonsmokers.
"I have a lot of patients who have never smoked," said Dr Heather Wakelee of Stanford University in California, who led the study. She said it was not clear why women were more likely to get lung cancer even if they had never smoked.
Writing in the Journal of Clinical Oncology, Dr Wakelee and epidemiologist Ellen Chang said they tracked the incidence of lung cancer in more than a million people aged 40 to 79.
Dr Chang said that because more men smoked than women, women might be more likely to be exposed to secondhand smoke, even when classified as never having smoked.
"We know that secondhand smoke does increase the risk of lung cancer so it's likely that a lot of these cases we observe are attributable to that."
- REUTERS
