Dr Steven B. Markowitz of Queen’s college, New York, says, “The interactions between asbestos exposure, asbestosis and smoking, and their influence on lung cancer risk are incompletely understood,”

“In our study of a large cohort of asbestos-exposed insulators and more than 50,000 non-exposed controls, we found that each individual risk factor was associated with increased risk of developing lung cancer, while the combination of two risk factors further increased the risk and the combination of all three risk factors increased the risk of developing lung cancer almost 37-fold.”

Study conducted on smokers and non smokers

Researchers carried out their study on both smokers and non smokers.  They picked out a total of 2,377 long-term North American insulators who would have been exposed to asbestos over a long period of time, and 54,243 male blue collar workers who had never been exposed to asbestos.

The results showed that amongst the people who didn’t smoke, if they were exposed to asbestos then their  chances of developing lung cancer and dying increased 5.2-fold, but if they were a smoker and exposed to asbestos then that likelihood increased to more than 28-fold.

For the insulators who quit smoking, the numbers of those dying from lung cancer greatly reduced after having stopped smoking for 10 years – the number of deaths fell from 177 per 10,000 among those who currently smoked to just 90 deaths per 10,000 for those who no longer smoked.

And the results were even greater for those who quit smoking for 30 years or more.

Dr  Markowitz said, “Our study provides strong evidence that asbestos exposure causes lung cancer through multiple mechanisms,” said Dr. Markowitz. “Importantly, we also show that quitting smoking greatly reduces the increased lung cancer risk seen in this population.”