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People who have never smoked develop about 10 to 15 percent of all lung cancers. If no-smoke lung cancer were considered a separate disease, it would still be one of the top ten cancer killers. Recent medical journal articles report that it is different, enough that researchers should consider separate studies for never smokers.
The bad news is, no-smoke lung cancer is more likely to affect women and younger adults. The good news is, it's not as deadly as the more common smoke-related cases. In a study of surgical removal of stage 1 non-small cell lung cancer, patients who had never smoked had a 10-year survival rate of 84.9 percent. Patients with the same diagnosis and treatment who had a history of smoking had a 10-year survival rate of only 36.7 percent.
In addition, no-smoke lung cancer responds better to chemotherapy. Researchers have identified one molecular mechanism for cancer as mutations in the epidermal growth factor receptor, EGFR. There are drugs called EGFR tyrosine kinase inhibitors to target this type of cancer. Two mentioned in Reference 1 are erlotinib (Tarceva) and getitinib (Iressa). Both drugs have very nice looking websites advertising their benefits in treating lung cancer. What they don't tell you is that the EGFR mutation is rare in lung cancer patients with a smoking history. Reference 1 reports that smokers are more likely to have KRAS mutations and lung cancers that demonstrate no response to these drugs. On the other hand, EGFR mutations are common in no-smoke lung cancers, and these cases respond well to this class of drugs.
Even for advanced lung cancer without active treatment, never smokers come out ahead. In the placebo arms of chemotherapy drug trials for patients with advanced recurrent disease, never-smokers had a 1-year survival rate of 29 percent, while smokers and former smokers had a 1-year survival rate of only 18 percent.
Second hand smoke contains the same carcinogens that active smokers inhale, so we may expect some never smokers to have cancers similar to those of smokers. For other no-smoke lung cancers, risk factors include:
1. Family history
2. History of other lung disease, including emphysema, chronic bronchitis, asthma, pneumonia, and tuberculosis
3. Exposure to other inhaled carcinogens including industrial chemicals
The authors of Reference 1 recommend more research focused on no-smoke lung cancers.
References:
1. Rudin CM et al, “Lung cancer in never smokers: Molecular profiles and therapeutic implications”, Clin Cancer Res. 2009 Sept 15; 15(18): 5646-61.
2. Brenner DR et al, “Lung cancer risk in never-smokers: A population-based case-control study of epidemiologic risk factors”, BMC Cancer 2010; 10: 285.
Linda Fugate is a scientist and writer in Austin, Texas. She has a Ph.D. in Physics and an M.S. in Macromolecular Science and Engineering. Her background includes academic and industrial research in materials science. She currently writes song lyrics and health articles.
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I'm glad you wrote about this topic during Lung Cancer Awareness Month. Lung cancer is so much more than just "a smoker's disease" and many lung cancer-causing chemicals are around us everyday, like asbestos - check out http://www.BanAsbestosNow.com if you really would like to help make a difference - and radon, to just name two. Like you mentioned, education and awareness about the risk factors beyond smoking are key to preventing this awful disease.
November 17, 2010 - 11:51amThis Comment