Tuesday, March 22nd, 2011.
Lung cancer is the most common type of cancer worldwide, resulting in 1.4 million deaths annually1. In the US, more than 150,000 deaths resulted from lung cancer in 20102. Although lung cancer can have numerous causes, smoking is a huge and well-known contributor to lung cancer deaths, with some 90% of all lung cancer cases a result of smoking tobacco.
While there can be no discounting smoking’s ill health effects, the flood of information on smoking’s risks can drown out other causes of lung cancer. A recent study in The Annals of Occupational Hygiene, a research journal on hazards and risks to health resulting from work, highlights another contributor to lung cancer: asbestos.
Asbestos as a cause of lung cancer is often ignored because of smoking. One reason for this is readily revealed in “The effect of smoking on the risk of lung cancer mortality for asbestos workers in Great Britain (1971-2005)”: among asbestos workers, smoking is more common than in the general population. The study followed asbestos workers from 1971 until 2005, at which point some 53% of asbestos workers were still active smokers. In contrast, 45% of the general population in Great Britain smoked in 1971, and that number dropped to 24% by 2005.
While either cigarette smoking or asbestos may be the cause of lung cancer, together, they create an exceptionally high risk. One cannot simply add the risk associated with each carcinogen together and determine the risk that the two create in individuals exposed to both.
This synergistic connection between asbestos and smoking is well known among researchers who specialize in studies like the one cited above. In fact, a September 2010 journal article covering asbestos workers in China (“Lung cancer mortality from exposure to chrysotile asbestos and smoking: a case control study within a cohort in China”) found that the total risk of lung cancer was one and a half times what would be expected if the risk associated with smoking and the risk associated with asbestos exposure were added together3.
In the Chinese study, no completely unexposed control group was compared to asbestos exposed and/or smoking groups studies. Other studies that have compared non-asbestos exposed, non-smoking workers to asbestos exposed, smoking workers found the latter group fifty or more times likely to develop lung cancer over the former group4.
While researchers may be aware of this deadly mix, many primary care physicians are unaware of these connections. Without a thorough patient history, the connection between a patient’s lung cancer and their asbestos exposure may never be made, especially if they smoked. Unfortunately, with a smoker, many people, doctors included, stop looking at other culprits for a patient’s lung cancer. It’s important to note, however, that although smoking is a great risk factor in a lung cancer diagnosis, only 10% of smokers will develop lung cancer.
Asbestos attorneys see thousands of people diagnosed with lung cancer each year, and Dave Chervenick is no exception. A shareholder at Goldberg, Persky, and White, a law firm that has specialized in asbestos cases for more than 30 years, Chervenick notes “If there was one thing I could impress upon our clients with lung cancer, it’s that smoking doesn’t negate your asbestos exposure, and in fact, it’s an important factor related to it.”
Many of Chervenick’s asbestos lung cancer clients were already suffering from another asbestos-related disease, such as asbestosis, before being diagnosed. “When one of our asbestosis clients later develops lung cancer, it’s a little easier for them to see the connection,” Chervenick explains, “however, you don’t have to have asbestosis to develop lung cancer.”
Asbestosis is a scarring of the lung tissues resulting from breathing in asbestos fibers. The small, sharp, and indestructible asbestos bodies lodge in the lungs, causing a buildup of scar tissue that makes it hard for the lungs to expand and contract and complete their job of exchanging carbon dioxide for oxygen.
Asbestosis definitively reveals that you’ve been exposed to asbestos, and because of that, indicates you’re at increased risk of developing an asbestos-related lung cancer. The number of lung cancer cases attributable to asbestos exposure each year in the US is estimated at 3,400 to 8,500. It is likely higher however, thanks to poor tracking mechanisms and a lack of complete worker histories.
It is also not unusual for a worker to be unaware they worked with asbestos. “I’ve had people tell me they don’t believe they ever handled asbestos products,” Chervenick says, “however, after I mention a particular brand of insulation, or a type of sealer, they’ll say ‘well, yes, I worked with that.’ Well, that item contained 10%, or 30%, or even 50% asbestos.”
In order to reduce the risk among asbestos workers and smokers, eliminating exposure to both is recommended. Some studies indicate a reduction in the risk of lung cancer within five years of smoking cessation. The numbers associated with removing asbestos exposure vary, but researchers note “that even if the risk of lung cancer does not decrease following cessation of asbestos exposure, removal from exposure would prevent cumulative dosage.” 1
In Great Britain, researchers estimate that smoking and/or asbestos exposure result in 96% of lung cancer deaths. Using that guideline on worldwide deaths, that could mean more than 1.3 million lives could be saved from lung cancer if smoking and asbestos were eliminated.
Gillian Frost, Andrew Darnton, and Anne-Helen Harding. “The effect of smoking on the risk of lung cancer mortality for asbestos workers in Great Britain (1971–2005).” The Annals of Occupational Hygiene. First published online January 20, 2011 doi:10.1093/annhyg/meq089.SEER Stat Fact Sheets: Lung and Bronchus. Surveillance Epidemiology and End Results; National Cancer Institute.You can follow any responses to this entry through the RSS 2.0 feed.
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