Urine test may determine
if a smoker is at risk for lung cancer
Monday, April 20,
2009
Researchers may have uncovered why lung cancer afflicts some
smokers and not others, according to data presented at the American
Association for Cancer Research 100th Annual Meeting 2009.
"A history of smoking has always been thought of as a predictor of
lung cancer, but it is actually not very accurate," said Jian-Min
Yuan, Ph.D., M.D., associate professor of public health at the
University of Minnesota. "Smoking absolutely increases your risk,
but why it does so in some people but not others is a big
question."
Yuan and colleagues hypothesized that the presence of the
metabolite NNAL in a patient's urine might predict risk of lung
cancer. This metabolite has been shown to induce lung cancer in
laboratory animals, but the effect in humans had not yet been
studied.
Researchers collected data from 18,244 men enrolled in the Shanghai
Cohort Study and 63,257 men and women from the Singapore Chinese
Health Study. In addition to in-person interviews to assess levels
of cigarette smoking, dietary and other lifestyle factors,
researchers collected blood and urine samples from more than 50,000
patients.
To evaluate the impact of NNAL, researchers identified 246 current
smokers who later developed lung cancer and 245 smokers who did not
develop lung cancer during the 10-year period following initial
interview and collection of urine samples.
Levels of NNAL in the urine were divided into three groups.
Compared to those with the lowest levels, patients with a mid-range
level of NNAL had a 43 percent increased risk of lung cancer, while
those at the highest level had a more than two-fold increased risk
of lung cancer after taking into account the effect of number of
cigarettes per day, number of years of smoking, and urinary levels
of cotinine on lung cancer risk.
Levels of nicotine in the urine were also calculated. Those with
the highest levels of nicotine and NNAL had an 8.5-fold increase in
the risk of lung cancer compared with smokers who had the lowest
levels after accounting for smoking history.
"Smoking leads to lung cancer, but there are about 60 possible
carcinogens in tobacco smoke, and the more accurately we can
identify the culprit, the better we will become at predicting
risk," said Yuan.
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American Association for Cancer Research
Thanks to American Association for
Cancer Research for this article.