Urine Test for Lung Cancer?
Researchers Developing Urine Test to Determine Smokers at Highest Risk for Lung Cancer
Developing a Urine Test continued...
At the time of enrollment, urine and blood samples were collected from all the participants and frozen for future use. They were also asked to answer a battery of questions, including whether they smoked, how much they smoked, and for how long they smoked.
For the new analysis, the researchers focused on 245 smokers in the studies who developed lung cancer and 245 smokers who didn’t get cancer.
Then they thawed their urine samples and measured levels of NNAL, a byproduct of one of the most potent tobacco lung carcinogens identified to date.
“When you smoke, you suck in about 60 carcinogens. One of the most potent, called NNK, breaks down and becomes NNAL in the body,” Yuan says.
NNAL has been shown to induce lung cancer in laboratory animals, but the effect in humans had not yet been studied, he says.
Then the smokers were divided into three groups based on their levels of NNAL in the urine.
Compared with those with the lowest levels, people with a mid-range level of NNAL had a 43% increased risk of lung cancer. Those with the highest levels had more than twice the risk of lung cancer.
Then the researchers measured a byproduct of nicotine, called cotinine, in the urine.
Smokers with the highest levels of both cotinine and NNAL had an 8.5-fold increase in the risk of lung cancer compared with smokers who had the lowest levels.
The findings held true even after taking into account the number of cigarettes smoked per day, the number of years of smoking, and other factors.
The next step is to measure another tobacco-carcinogen byproduct called PAH in the participants’ urine and look at whether high levels of all three chemicals even further raises risk, Yuan says.
“The idea is to build up a risk model that incorporates many of these biomarkers as well as smoking history, so we can best identify which smokers will eventually develop lung cancer,” he says.