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Thoracic Surgery > Lung Cancer > Understanding Lung Cancer
Understanding Lung Cancer
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Cancer is the result of defective genes. The defects can be inherited and almost always result from exposure to carcinogens. Carcinogens are cancer causing agents such as chemicals, radiation or viruses.
Carcinogens associated with lung cancer include:
- All forms of smoking
- Exposure to second hand smoke
- Exposure to Radon (leading cause of lung cancer in non-smokers)
- Exposure to asbestos
- Air pollution
*Not all people exposed to carcinogens will develop cancer.
Lung cancer results from the abnormal growth of cells in one or both lungs. Each of the cells in our bodies
are programmed with specific functions. Carcinogens may cause direct damage to a cells program
or alter the body s natural ability to fight infections and destroy abnormal cells. If a change occurs in
the programming, the cell is said to have mutated or changed its normal growth pattern. When cells
continue to mutate they begin to grow abnormally. Some of the abnormal growths are malignant or
cancerous. Abnormal growths that are not cancerous are referred to as benign.
Progression of lung cancer begins with excessive growth of abnormal cells known as hyperplasia.
Following hyperplasia, division of the damaged (abnormal) cells occurs this is referred to as dysplasia.
These cells are pre-malignant (pre-cancerous) and no longer look or function like normal cells. Normally
these cells can be eliminated by a healthy immune system. If left unchecked they will multiply out of
control. Doubling time refers to the time it takes for cancer cells to divide and double in number. Lung
cancer doubling times range from 30-180 days. The accumulation of abnormal cells forms a mass of
abnormal tissue known as a tumor. Like other cells, these cells require a blood supply to function.
Angiogenesis is the development of blood vessels by the tumor that allows the cancer to spread and
invade adjacent tissue. When migration or movement of the tumor to other parts of the body occurs by
way of the blood stream or the lymphatic system, the tumor is said to have metastasized.
Usually lung cancer begins in the lining of one of the bronchial tubes or in the alveoli (air sacs). These
tissues are directly exposed to the air and/or carcinogens making them particularly vulnerable.
Hyperplasia and dysplasia are the pre-malignant (pre-cancerous) phases of abnormal cell development
that can occur over time (sometimes decades) develop into lung cancer. Once cancer cells develop
growth is more rapid and metastasis can occur. Reduction of risk factors, early diagnosis, staging and
treatment of lung cancer is imperative for a successful outcome.
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References:
- Alliance for Lung Cancer Advocacy, Support and Education. Education: Early Detection and Diagnostic Imaging (2001). www.alcase.org
- American Cancer Society. Cancer Facts and Figures (2003). www.cancer.org
- American Cancer Society. Cancer Facts and Figures (2004). www.cancer.org
- American Cancer Society. Cancer Facts and Figures (2005). www.cancer.org
- National Center for Chronic Disease Prevention and Health Promotion. Cancer Prevention and Control. *Last accessed March 2005.
www.cdc.gov/cancer/lung
- National Institutes of Health, National Cancer Institute. Bethesda, MD: US Department of Health and Human Services. Fact Book (2003). www.cancer.gov
- Pass, H. et al. Lung Cancer Principles and Practice.2nd ed. Philadelphia: Lippincott Williams and Wilkins. 2000.
- Scott, W. Lung Cancer: A Guide to Diagnosis and Treatment.Omaha: Addicus Books. 2000.
- Henschke C, McCarthy P, Wernick S, Lung Cancer. Myth, Facts, Choices and Hope.New York: WW Norton & Co Ltd. 2002.
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