Cancer risk of those not smoking is calculated

WASHINGTON -- Up to 20 percent of women who develop lung cancer have never smoked, US researchers found in a study that suggests secondhand smoke may be to blame.

A survey of a million people in the United States and Sweden indicates that just 8 percent of men who get lung cancer are nonsmokers. That compares with American Cancer Society estimates of 10 percent to 15 percent for all lung cancer patients .

"I have a lot of patients who have never smoked," said Dr. Heather Wakelee of Stanford University in California, who led the study. "And because of the stigma, people are embarrassed to speak out about their disease. They feel like as soon as they say they have lung cancer, everyone judges them."

She said it is not clear why women may be more likely to get lung cancer even if they have never smoked.

"There is a lot of controversy over whether women are more susceptible to smoking at all, whether direct or secondhand smoke," Wakelee said.

Writing in yesterday's issue of the Journal of Clinical Oncology, Wakelee and epidemiologist Ellen Chang said they tracked the incidence of lung cancer in more than 1 million people ages 40 to 79. All had taken part in various studies of diet, lifestyle, and disease, some going back into the early 1970s.

Some groups were mostly white women, such as those in an ongoing nurse's study, while others included ethnically diverse groups, Wakelee said.

Among the women who never smoked, the lung cancer rate ranged from 14.4 to 20.8 cases per 100,000 women a year. In men, it was 4.8 to 13.7 per 100,000.