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Non-small cell lung cancer - Causes
- Highlights
- Introduction
- Causes
- Symptoms
- Risk Factors
- Lifestyle Changes
- Diagnostic Tests
- Staging Systems
- Treatment Options by Stages
- Surgical Procedures
- Radiation Treatments
- Chemotherapy Treatments
- Investigative Agents
Description
An in-depth report on the causes, diagnosis, treatment, and prevention of non-small cell lung cancer (NSCLC).Alternative Names
Lung cancer - non-small cell; NSCLC
Causes:
Cigarette Smoke. Smoking causes 87% of lung cancer deaths, and accounts for 30% of all cancer-related deaths. Cigarettes, nicotine, or both may contribute to lung cancer in one or more of the following ways:
- The smoke is the most dangerous component of the cigarette. Chemicals formed during smoking trigger genetic mutations that lead to cancer. When people inhale cigarette smoke, they bring into their lungs tar that includes over 4,000 chemicals, some of which are carcinogenic (cancer-causing). Other inhaled chemicals in cigarette smoke that may increase the risk for cancer include cyanide, benzene, formaldehyde, methanol (wood alcohol), acetylene (the fuel used in torches), and ammonia. Smoke also contains nitrogen oxide and carbon monoxide, both harmful gases.
- Nicotine itself may be a hazard. Some studies indicate that nicotine has a role in causing cancer. Whether or not these studies apply to long-term use of nicotine replacement products (such as patches), or to cigarette smoking, is still unclear. The studies should certainly not discourage people from using nicotine replacement methods for quitting. However, these studies may suggest that people should not use these products on a long-term basis, unless they are the only way to stay off cigarettes.
Radon. Radon is a gas produced naturally by the breakdown of uranium. It is often present in the soil and in water and can seep into any dwelling. Radon is the second leading cause of lung cancer.
Other Contributors. Toxic particles leading to precancerous changes in the lung are also found in marijuana. Multiple studies report an association between abnormal lung changes and marijuana smoking.
There is considerable debate over the lung cancer risk posed by depleted uranium used in military weapons (such as in the Gulf and Balkan conflicts).
Other lung carcinogens include asbestos, arsenic, certain petrochemicals (materials made from crude oil or natural gas), and other airborne (carried through the air) byproducts of various mining and manufacturing processes.
Click the icon to see an image of the tobacco plant.
Genetic Mutations
Genetic mutations that cause cancer generally occur in two types of genes:
- Tumor-suppressor genes, which prevent cells from endlessly copying themselves
- Proto-oncogenes, which encourage cells to keep making copies of themselves [when a proto-oncogene changes (becomes mutated), it is then called an oncogene]
Damage to either type of gene can cause a mutation that results in uncontrolled division of cells. This uncontrolled division forms tumors.
It is unlikely that a single specific abnormality causes all lung cancer. It probably takes a variety of mutations to start the devastating chain of events leading to cancer. The following mutations are among those under investigation:
- BPDE-caused mutations: The chemical BPDE, a byproduct of tobacco smoke, is involved with a number of genetic mutations, including those to an oncogene called K-ras and to three tumor-suppressor genes known as p53, PPP2R1B, and p16. (Tumors that contain the p53 mutation may also be more resistant to chemotherapy.)
- Rb mutations: Another important contributor to lung cancer is a genetically defective protein called retinoblastoma (Rb), which is associated with very aggressive tumors. Low levels of the normal Rb gene may sometimes predict aggressive cancer, especially in patients with small cell lung cancer.
- Abnormalities in the FHIT gene: Such abnormalities may cause the cells lining the lung to become more vulnerable to the effects of tobacco smoke and other cancer-causing substances.
- Alpha1-antitrypsin mutations: People who carry a common variation in the gene for alpha1-antitrypsin -- a substance that normally protects the walls of the alveoli in the lungs -- are 70% more likely to develop lung cancer than those without the mutation, regardless of whether they smoke.
Resources
- www.cancer.gov -- National Cancer Institute
- www.cancer.org -- American Cancer Society
- www.cancercare.org -- Cancer Care
- www.lungusa.org -- The American Lung Association
- www.asco.org -- American Society of Clinical Oncology
- www.alcase.org -- Alliance for Lung Cancer
- www.lungcancer.org -- Joint project of Cancer Care and the Oncology Nursing Society
- www.nccn.org -- National Comprehensive Cancer Network
- www.lungcanceronline.org -- Lung cancer information
- www.epa.gov/iaq/radon -- National radon information
- www.clinicaltrials.gov -- Find clinical trials
- www.cancer.gov/clinicaltrials -- Find clinical trials
References
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- Reviewed last on: 7/23/2009
- Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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