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Medical Author:

Michael C. Fishbein, MD

Michael C. Fishbein, MD

Dr. Fishbein received his undergraduate and medical degrees from the University of Illinois. He completed a residency in anatomic and clinical pathology at Harbor General Hospital/UCLA Medical Center. He is board certified in anatomic and clinical pathology.

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Medical Editor:

Jay W. Marks, MD

Jay W. Marks, MD

Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

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In this Article

• Smoker's lung introduction
• What is the structure of the normal lung?
• What processes determine normal function of the lung?
• What are the abnormalities (diseases) in smoker's lung?
• What happens to the lung in emphysema?
• How does emphysema come about?
• Why does smoker's lung look black?
• What happens to the airways in chronic bronchitis?
• Are smokers with COPD predisposed to developing pneumonia?
• What about lung cancer in smokers?
• Are any of the pulmonary consequences of smoking reversible?
• From what do smokers die?
• Patient Comments: Smokers' Lung - COPD and Pneumonia
• Smoker's Lung: Pathology Photo Essay Index

Smoke contains more than 60 carcinogens (chemicals that cause cancer) and about 200 known toxic substances. Scientists are still learning about how carcinogens work and why only some people who smoke get lung cancer. Genes are the hereditary units in chromosomes and appear to have a lot to do with a person's susceptibility to cancer. The genes are made up of DNA (deoxyribose nucleic acid), which controls how cells divide and reproduce (proliferate). Damage to DNA from cigarette smoke can lead to uncontrolled cell proliferation and growth, which is what cancer is finally all about.

It is of interest that some smokers develop COPD, some develop lung cancer, some get neither, and some get both. We really don't know the reason for these different susceptibilities. Besides that, lung cancer from smoking can take a number of different forms. For example, the cancer cells can resemble cells of the skin (squamous cell carcinoma), cells of the bronchial glands (adenocarcinoma), or specialized cells of the nervous system (neuroendocrine carcinoma). Figure 8 shows an adenocarcinoma in a smoker's lung with severe emphysema.

Figure 8: SMOKER'S LUNG WITH EMPHYSEMA AND CANCER

What do you think the outcome (prognosis) is for this patient with lung cancer? Well, almost all types of lung cancer are particularly deadly. Thus, if a lung cancer is more than an inch or so in diameter (as in this patient) or has spread outside of the lung, fewer than 50% of affected individuals will survive another 5 years. And that is so even with the best of therapy. What's more, consider a cancer that is less than an inch in size (or not large enough to be seen on a chest X-ray) and is confined to the lung. Unfortunately, even if such a cancer is completely removed by surgery, about 25% of individuals will still die from the cancer in less than 5 years from the time of diagnosis. The reason for this poor outcome (prognosis) is that lung cancers tend to spread (metastasize) early in the course of disease to other organs, most often the brain, liver, and bone.