Smoking significant contributor to asbestos-related lung cancer
medwireNews: Quitting smoking significantly reduces a person's chance of getting lung cancer after being exposed to asbestos, suggest study findings.
"The interactions between asbestos exposure, asbestosis and smoking, and their influence on lung cancer risk are incompletely understood," said lead author Steven Markowitz (Queens College, City University of New York, USA) in a press statement.
"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," he explained.
Markowitz and colleagues analyzed data collected from 2377 men who worked as insulators and had been exposed to asbestos and from 54,243 blue-collar workers who had not been exposed to asbestos and who acted as controls.
As reported in the American Journal of Respiratory and Critical Care Medicine, between 1981 and 2008 lung cancer caused 339 (19%) of deaths among insulators.
In nonsmokers, exposure to asbestos and asbestosis increased the risk for lung cancer 3.6- and 7.4-fold, respectively, compared with nonsmoking, nonexposed controls. Smoking without exposure to asbestos also increased the risk for lung cancer 10.3 fold compared with controls, as might be expected from previous research.
In men who had been exposed to asbestos who were also smokers, the risk for lung cancer was additive and increased 14.4-fold compared with controls. In those who had all three factors, the risk was 36.8-fold higher than that of nonsmoking, nonexposed controls.
Markowitz and team found that among insulators who quit smoking, lung cancer mortality dropped from 177 per 10,000 smokers to 90 per 10,000 nonsmokers within 10 years. At 30 years after quitting, lung cancer mortality was similar in ex- and never smokers exposed to asbestos.
While "our study provides strong evidence that asbestos exposure causes lung cancer through multiple mechanisms," said Markowitz, "importantly, we also show that quitting smoking greatly reduces the increased lung cancer risk seen in this population."
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013
By Helen Albert, Senior medwireNews Reporter