New research presented at the American Association for Cancer Research (AACR) annual meeting concludes that testing for high levels of a tobacco carcinogen found in urine could be used to predict the risk of lung cancer among smokers, Reuters Health reported April 22.

NNAL is a tobacco-specific metabolite of the carcinogen NNK; both NNK and NNAL are known to induce lung cancer in laboratory animals. Investigators examined the risk of lung cancer associated with NNAL in urine samples obtained from cigarette smokers enrolled in two large population-based studies.

The study found that smokers who had the highest levels of urinary NNAL and cotinine — a biomarker for nicotine exposure — had an 8.5-fold higher risk of lung cancer compared to smokers with comparable smoking histories but with low levels of NNAL and cotinine in their urine. “Urinary levels of total NNAL were significantly associated with risk of lung cancer in a dose-dependent manner,” the investigators reported.

Jian-Min Yuan, lead author of the study, noted that the study results “directly link NNK exposure to lung cancer development in humans,” adding that the NNK and NNAL biomarkers “can serve as the starting point for an individual-based, predictive model for lung cancer risk in a smoker.”

The study appeared in the April 2009 issue of the journal Cancer Research.