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LUNG CANCER
What is lung cancer?
Lung Cancer occurs when cells in the lungs
start to grow rapidly in an uncontrolled manner. Lung
Cancer can start anywhere in the lungs and affect any part of
the respiratory system. It is the leading cause of cancer
deaths in both men and women. Some well-established risk
factors are associated with lung cancer. Changing your
lifestyle can, over time, gradually reduce some of your risk
factors for developing lung cancer.
What causes lung cancer?
Researchers have identified several causes of lung cancer. Most
lung cancers are related to the use of tobacco. Harmful
substances, called carcinogens, in tobacco smoke damage the
cells in the lungs. Experts estimate that 85% to 90% of lung
cancers are caused by tobacco smoke.
1,
2
About 1 in every 4 adults smoke cigarettes, significantly
increasing the risk of lung cancer in these people. Even
secondhand tobacco smoke is a risk factor for lung cancer.
Besides tobacco use, exposure to harmful substances such as
arsenic, asbestos, radioactive dust, or
radon can
increase the risk for lung cancer. Having a combination of risk
factors—for example, being a smoker who is also exposed to
asbestos—greatly increases your risk of getting lung cancer.
Radiation exposure from occupational, medical, or environmental
sources may also increase your risk for lung cancer.
The most important prevention measure is to not use any tobacco.
If you do use tobacco, you can reduce your risk for lung cancer
by quitting. Your risk will gradually decrease over 10 to 15
years as your lungs recover.
3
Quitting smoking reduces your risk for developing cancer and
your risk continues to decrease as long as you don't smoke. The
benefit of quitting smoking is greater if it occurs at a young
age.
What types of
lung cancer are there?
There are two main types of lung cancer: non–small cell lung
cancer and small cell lung cancer. The cancer cells of these two
types of lung cancer look different under a microscope, grow and
spread in different ways, and are treated differently.
Non–small cell lung cancer is more common than small cell lung
cancer. Over 80% of all lung cancers are non–small cell cancer.
4
It generally grows and spreads more slowly than small cell lung
cancer. The types of non–small cell lung cancer are:
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Adenocarcinoma. About 35% to 40% of
non–small cell lung cancers are adenocarcinoma.
5
This type often begins near the
outside surface of the lung and may vary both in size and
how fast it grows. Adenocarcinoma is likely to spread to
lymph nodes and other organs. This type is more common than
other types of lung cancer in women, nonsmokers, or former
smokers.
-
Squamous cell carcinoma, also called
epidermoid carcinoma. About 25% to 35% of all lung cancers
are squamous cell.
5
This type usually begins in one of the
larger airway tubes (bronchi), generally grows more slowly
than the other types of non–small cell cancer, and may vary
in size from very small to very large. Squamous cell may
spread to nearby lymph nodes or to other organs.
-
Large cell carcinoma. About 5% to 10%
of all lung cancers are large cell.
5
This type often begins near the
surface of the lung and usually is large when diagnosed.
Large cell is likely to spread to lymph nodes and other
organs.
-
Adenocarcinoma with other, less common
subtypes, such as clear cell or mucinous adenocarcinoma.
This occurs less often.
4
-
Small cell lung cancer, which used to
be called oat cell cancer, is less common than non–small
cell lung cancer, accounting for about 20% of lung cancers.
4
This type of cancer grows very rapidly
and in over 80% of cases has already spread to other organs
in the body by the time it is diagnosed.
4
Small cell lung cancer is more
strongly linked to smoking than non–small cell cancer.
4
How will I know I have lung cancer?
You may not know. Early lung cancer
rarely causes symptoms. In its advanced stage, the cancer
may interfere with normal lung function. Respiratory
problems, such as a cough, wheezing, or shortness of breath,
may be the first symptoms of lung cancer.
Lung cancer eventually spreads
(metastasizes) to nearby lymph nodes or other tissues in the
chest, such as the lining of the lungs (pleura) or around
the heart (pericardium)
or the other lung. In many cases, lung cancer may also
spread to other organs—such as the brain, liver,
adrenal glands,
or bones—and cause other symptoms that prompt you to seek
medical evaluation.
How is lung cancer diagnosed?
A health professional evaluates your
symptoms, medical history, smoking history, and exposure to
environmental and occupational substances and your family
history of cancer to help determine whether lung cancer may
be the cause of your respiratory symptoms.
Lung cancer is usually first detected
with a chest X-ray. Tests to diagnose non–small cell or
small cell lung cancer can also help determine the
stage
of the cancer—whether it is confined to your lung or has
spread to other parts of your body.
What are Conventional
Treatment Options?
Treatment for lung cancer depends on
the stage of your cancer and may include surgery (removing
the cancer), radiation therapy (using high-dose X-rays or
other high-energy rays to kill cancer cells), or
chemotherapy (using medications to kill cancer cells). A
combination of treatments may also be used.
Your treatment choice and long-term
outcome (prognosis) depend on:
Lung cancer treatment may be moderately successful in
early-stage disease, but only about 15% of lung cancers are discovered in
the early stages.
6 Treatment is
not very successful if the lung cancer is advanced at the time of diagnosis.
The overall 1-year survival rate is about 42%. At 5 years, the survival rate
is about 15%.
6
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References
Citations
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American Cancer Society (2005). What are the key
statistics for lung cancer? Detailed Guide: Lung Cancer.
Available online:
http://www.cancer.org/docroot/CRI/content/CRI_2_4_1X_What_are_the_key_statistics_for_lung_cancer_26.asp?sitearea=CRI&viewmode=print&.
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Miller YE (2004). Lung cancer and other pulmonary
neoplasms. In L Goldman, D Ausiello, eds., Cecil Textbook of
Medicine, 22nd ed., pp. 1201–1208. Philadelphia: Saunders.
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Crawford J (2004). Lung cancer. In DC Dale, DD
Federman, eds., ACP Medicine, section 12, chap. 8. New
York: WebMD.
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American Joint Committee on Cancer (2002). Lung. In
AJCC Cancer Staging Manual, 6th ed., pp. 167–177. New
York: Springer.
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Jablons D, et al. (2003). Neoplasms of the lung. In LW
Way, GM Doherty, eds., Current Surgical Diagnosis and
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Bain C, et al. (2004). Lung cancer rates in men and
women with comparable histories of smoking. Journal of the
National Cancer Institute, 96(11): 826–834.
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Humphrey LL, et al. (2004). Lung cancer screening
with sputum cytologic examination, chest radiography, and computed tomography:
An update for the U.S. Preventive Services Task Force. Annals
of Internal Medicine, 140(9): 740–753.
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National Cancer Institute (2004). Lung Cancer PDQ: Screening Health Professional Version.
Available online:
http://www.cancer.gov/cancertopics/pdq/screening/lung/HealthProfessional/page1.
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National Cancer Institute (2005). Lung Cancer PDQ: Treatment—Health Professional Version.
Available online:
http://www.cancer.gov/cancertopics/pdq/treatment/non-small-cell-lung/healthprofessional.
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International Adjuvant Lung Cancer Trial
Collaborative Group (2004). Cisplatin-based adjuvant chemotherapy in patients
with completely resected non–small-cell lung cancer. New
England Journal of Medicine, 350(4): 351–360.
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Centers for Disease Control and Prevention (2005).
Lung cancer statistics. Available online:
http://www.cdc.gov/cancer/lung/statistics.htm.
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Goodman GE, et al. (2004). The beta-carotene and
retinol efficacy trial: Incidence of lung cancer and cardiovascular disease
mortality during 6-year follow-up after stopping beta-carotene and retinol
supplements. Journal of the National Cancer Institute,
96(23): 1743–1750.
-
Food and Drug Administration (2004). FDA statement on
Iressa. FDA Public Health Web Notification. Available
online: http://www.fda.gov/bbs/topics/news/2004/new01145.html.
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Chesnutt MS, Prendergast TJ (2005). Pulmonary
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McGraw-Hill.
Other Works Consulted
- Centers for Disease Control and Prevention (2005).
Lung cancer statistics. Available online:
http://www.cdc.gov/cancer/lung/statistics.htm.
- National Comprehensive Cancer Network and American
Cancer Society (2004). Non–Small Cell Lung Cancer: Clinical
Practice Guidelines in Oncology, version V.1.2005. Jenkintown, PA:
National Comprehensive Cancer Network.
- National Comprehensive Cancer Network and American
Cancer Society (2004). Small Cell Lung Cancer: Clinical
Practice Guidelines in Oncology, version V.1.2005. Jenkintown, PA:
National Comprehensive Cancer Network.
- Neville A (2004). Lung cancer. Clinical Evidence (11): 2031–2053.
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