Study Finds Higher Lung Cancer Rate in Women Nonsmokers
WASHINGTON, DC -- February 14, 2007 -- Stanford University researchers recently published a study finding that up to 20 percent of women who develop lung cancer have never smoked (Journal of Clinical Oncology, Vol 25, No 5 (February 10), 2007: pp. 472-478). In comparison, the study found that approximately 8 percent of men who develop lung cancer are nonsmokers. The study suggests secondhand smoke may be to blame for the higher incidence of lung cancer in nonsmoking women.
The researchers used multiple collections of data from more than one million people, ranging in age from 40 to 79, in the United States and Sweden. They calculated the lung cancer incidence rates of new cases per person-year, representing every year that someone was included in the study. Among women who never smoked, the lung cancer incidence rate ranged from 14.4 per 100,000 to 20.8 cases per 100,000 women per year. In men, it ranged from 4.8 to 13.7 per 100,000. This translates to about 20 percent of females and 8 percent of male lung cancer patients who have never smoked (Press Release, February 9, 2007). Incidence rates for lung cancer were approximately 10 to 30 times higher in smokers. Prior to the study, oncologists had speculated that about 10 percent to 15 percent of lung cancer patients were nonsmokers.
"We can actually put numbers on it now," explained lead author Heather Wakelee, M.D., assistant professor of medicine at Stanford. "Before this, we could only estimate based on our own census." (Press Release, Stanford School of Medicine, February 8, 2007)
Ellen Chang, ScD, an epidemiologist at the Northern California Cancer Center and a member of the Stanford Comprehensive Cancer Center, co-author of the study, explained that because more men smoke than women, women may be more likely to be exposed to secondhand smoke even when they are classified as nonsmokers. "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," she said in a statement.
Smoking is the leading cause of lung cancer, but environmental and occupational factors such as exposure to radon, chromium, arsenic and asbestos are associated with lung cancer . "Non-smoking-associated lung cancer is an increasingly important issue," Chang said in a press release, "even if only because the population of never-smokers is growing." The research team hopes that by studying lung cancer in nonsmokers, they can also alleviate some of the stereotypes associated with the disease.
Finding Out More About Secondhand Smoke
The Surgeon General's report, Health Consequences of Involuntary Exposure to Tobacco Smoke, can be found on the Health and Human Resources web site. You will need Adobe Acrobat to open the files containing the report. If you do not already have this software, you may download a free copy from the Adobe web site.
Secondhand smoke can cause lung cancer, heart disease and respiratory problems including coughing, chest pain, reduced lung function, increased asthma attacks, and increased rates of pneumonia and bronchitis (American Cancer Society). The American Cancer Society projects that lung cancer will be diagnosed in 213,000 Americans in 2007 and kill 160,000.