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Women double risk for lung cancer { December 2 2003 } Original Source Link: (May no longer be active)
http://www.nationalpost.com/home/story.html?id=4D0A075E-EDEB-47C3-B205-A9DEE94BD8C6http://www.nationalpost.com/home/story.html?id=4D0A075E-EDEB-47C3-B205-A9DEE94BD8C6
Lung cancer risk is double for women
Scientists baffled by shift in disease
Brad Evenson, National Post , with files from Sharon Kirkey, CanWest News Service
National Post; CanWest News Service
Tuesday, December 02, 2003
Female smokers face twice the risk of getting lung cancer as men who smoke, say scientists, although they do not know the reason for the difference.
Research to be presented today at the Radiological Society of North America's annual meeting in Chicago reviews 10 years worth of computed tomography (CT) screening.
"We found that women had twice the risk of developing lung cancer as men, independent of how much they smoked, their age, or the size and textures of nodules found in their lungs," said Claudia Henschke, a professor of radiology at New York Hospital/Cornell Medical Center in New York City.
"There is as of yet no clear consensus why women are at increased risk."
Less surprisingly, the study also found the risk for lung cancer rises with the quantity of tobacco smoked and as a smoker ages.
An estimated 21,000 new cases of lung cancer will be diagnosed in Canada this year, while 19,000 patients will die of the disease. The vast majority of cases -- about 87% -- are caused by direct tobacco use. Second-hand smoke is the chief risk factor among the rest.
According to the Canadian Cancer Society, about 12,200 men and 9,000 women will be diagnosed this year. But the landscape is shifting dramatically. Among women, new lung cancer cases and deaths continue to climb and are now three to four times as high as rates in 1974.
Among men, rates levelled off in the mid-1980s and have fallen consistently, reflecting the drop in tobacco consumption that began in the 1960s. Women did not start cutting back until the 1980s, and so they will not see a drop in cancer rates for a decade.
Verna Mai, director of preventive oncology at Cancer Care Ontario, said it is difficult to assess the U.S. findings because lung cancer is a slow-moving disease. "You tend to see the effects over a period of many years, so you don't see a direct cause and effect."
Dr. Henschke noted that more research is needed to prove women have a higher risk of the disease. "We have to make sure it's not because they are smoking more or started younger" or inhale more, she said.
But "if we find women are more susceptible, we really have to target those young women who are starting to smoke and make a special effort to reach out to them."
One of the hottest debates in lung-cancer research has been whether screening high-risk patients using CT scanners -- a form of X-ray machine -- can detect cancers at an early, treatable stage. Historically, X-ray machines could not detect small tumours with enough efficiency to justify screening millions of people as a preventive health measure. As a result, most lung cancers are not diagnosed until the patient has symptoms, when the disease is incurable.
But CT scanning is now so sophisticated, many doctors believe it should be used to screen high-risk patients.
Another study presented by the same team yesterday found annual CT screening for lung cancer in smokers can detect tumours at their earliest stage, when the cure rate is 80% or better.
Hundreds of private CT screening clinics have popped up across the United States and Canada, some mounted on tractor-trailers and driven from city to city, offering screenings for as little as $300.
"I was worried, so I had a scan," says Rachael Oliver, a Calgary pack-a-day smoker. "It was clean. I didn't expect anything to show up, really. It's worth paying for the peace of mind."
According to a Health Canada survey last year, more men (23%) than women (20%) smoke. But the trend is reversed among teenagers: 23% of girls aged 15 to 19 smoke, compared with 21% of boys in the same age group.
It's not known what may make smoking riskier for women, though some researchers have speculated estrogen, a natural growth hormone, may be partly to blame. Other genetic differences between men and women have also been implicated.
In the U.S. study, researchers examined 2,968 men and women age 40 and older who had smoked or still smoked cigarettes but had no cancer symptoms.
The goal was to determine which risk factors -- including age, gender and smoking history -- when combined with the shape and size of lung nodules found on CT scans, determined the chances of getting lung cancer. The study was part of a larger effort to evaluate the usefulness of annual CT screenings in people at high risk.
The researchers detected 77 lung cancers in the 2,968 men and women screened. They also found lung nodules, which can be a precursor to cancer, in 1,097 of the participants, who were all at high risk for lung cancer.
"We also found that the more you smoke -- and as you age -- the greater the chances of developing lung cancer," said Dr. Henschke, the study's lead author.
But without further research, Dr. Mai said it would be a decade before CT screening becomes a common public health measure.
SEEKING STUDY PARTICIPANTS:
Smokers and former smokers in the Toronto area are being sought by Princess Margaret Hospital for a study headed by Dr. Heidi Roberts, which is examining the use of low-dose CT screening to detect lung cancers at a stage when they are still curable. Interested volunteers over the age of 55 who smoke, or have smoked, one pack a day for at least 10 years, or half-a-pack a day for 20 years should contact Dr. Roberts at 416 946-4501, ext. 6318 for further details. Information on the international study can be found on the Internet at:www.ielcap.org
Ran with fact box "Seeking Study Participants" which had been appended to the story.; bevenson@nationalpost.com
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