Lung cancer is a disease of uncontrolled cell growth in tissues of the lung. This growth may lead to metastasis, which is the invasion of adjacent tissue and infiltration beyond the lungs. The vast majority of primary lung cancers are carcinomas of the lung, derived from epithelial cells.
Cancer of the lung, like all cancers, results from an abnormality in the body's basic unit of life, the cell. Normally, the body maintains a system of checks and balances on cell growth so that cells divide to produce new cells only when needed. Disruption of this system of checks and balances on cell growth results in an uncontrolled division and proliferation of cells that eventually forms a mass known as a tumor.
The lung is also a very common site for metastasis from tumors in other parts of the body. Tumor metastases are made up of the same type of cells as the original, or primary, tumor. For example, if prostate cancer spreads via the bloodstream to the lungs, it is metastatic prostate cancer in the lung and is not lung cancer.
Symptomps
Lung cancer originates from abnormalities in the basic unit of the body - the cell. In the normal state, cells divide and reproduce according to need. This is brought about by a system of checks and balances built into the organism.
Sometimes, however, this orderly system is disrupted and cells divide and proliferate in an uncontrolled manner. They form an abnormal mass referred to as a tumor. Although not all tumors are malignant, those that give rise to lung cancer symptoms are.
Tumors that are benign usually do not pose a threat and can be removed without spreading to other parts of the body. Malignant tumors, like those of lung cancer, multiply and spread aggressively. They tend to move to other - often distant - parts of the body, in a process called metastasis.
Lung cancer, in particular, tends to metastasize or spread at an early stage. This makes it difficult to treat and it is one of the most life-threatening cancers around. The malignancy can spread to practically any part of the body. However, certain organs are more prone to being affected - they include the liver, adrenal glands, bone and the brain.
Tumors that are benign usually do not pose a threat and can be removed without spreading to other parts of the body. Malignant tumors, like those of lung cancer, multiply and spread aggressively. They tend to move to other - often distant - parts of the body, in a process called metastasis.
Lung cancer, in particular, tends to metastasize or spread at an early stage. This makes it difficult to treat and it is one of the most life-threatening cancers around. The malignancy can spread to practically any part of the body. However, certain organs are more prone to being affected - they include the liver, adrenal glands, bone and the brain.
Lung Cancer Causes
Cigarette smoking is the most important cause of lung cancer. Research as far back as the 1950s clearly established this relationship.
Cancer of the lung, like all cancers, results from an abnormality in the body's basic unit of life, the cell. Normally, the body maintains a system of checks and balances on cell growth so that cells divide to produce new cells only when needed. Disruption of this system of checks and balances on cell growth results in an uncontrolled division and proliferation of cells that eventually forms a mass known as a tumor.
The lung is also a very common site for metastasis from tumors in other parts of the body. Tumor metastases are made up of the same type of cells as the original, or primary, tumor. For example, if prostate cancer spreads via the bloodstream to the lungs, it is metastatic prostate cancer in the lung and is not lung cancer.
Symptomps
Lung cancer originates from abnormalities in the basic unit of the body - the cell. In the normal state, cells divide and reproduce according to need. This is brought about by a system of checks and balances built into the organism.
Sometimes, however, this orderly system is disrupted and cells divide and proliferate in an uncontrolled manner. They form an abnormal mass referred to as a tumor. Although not all tumors are malignant, those that give rise to lung cancer symptoms are.
Tumors that are benign usually do not pose a threat and can be removed without spreading to other parts of the body. Malignant tumors, like those of lung cancer, multiply and spread aggressively. They tend to move to other - often distant - parts of the body, in a process called metastasis.
Lung cancer, in particular, tends to metastasize or spread at an early stage. This makes it difficult to treat and it is one of the most life-threatening cancers around. The malignancy can spread to practically any part of the body. However, certain organs are more prone to being affected - they include the liver, adrenal glands, bone and the brain.
Tumors that are benign usually do not pose a threat and can be removed without spreading to other parts of the body. Malignant tumors, like those of lung cancer, multiply and spread aggressively. They tend to move to other - often distant - parts of the body, in a process called metastasis.
Lung cancer, in particular, tends to metastasize or spread at an early stage. This makes it difficult to treat and it is one of the most life-threatening cancers around. The malignancy can spread to practically any part of the body. However, certain organs are more prone to being affected - they include the liver, adrenal glands, bone and the brain.
Lung Cancer Causes
Cigarette smoking is the most important cause of lung cancer. Research as far back as the 1950s clearly established this relationship.
- Cigarette smoke contains more than 4,000 chemicals, many of which have been identified as causing cancer.
- A person who smokes more than one pack of cigarettes per day has a risk of developing lung cancer 20-25 times greater than someone who has never smoked.
- Once a person quits smoking, his or her risk for lung cancer gradually decreases. About 15 years after quitting, the risk for lung cancer decreases to the level of someone who never smoked.
- Cigar and pipe smoking increases the risk of lung cancer but not as much as smoking cigarettes.
About 90% of lung cancers arise due to tobacco use. The risk of developing lung cancer is related to the following factors:
- the number of cigarettes smoked,
- the age at which a person started smoking, and
- how long a person has smoked (or had smoked before quitting).
Other causes of lung cancer include the following:
- Passive smoking, or secondhand smoke, presents another risk for lung cancer. An estimated 3,000 lung cancer deaths occur each year in the U.S. that are attributable to passive smoking.
- Air pollution from motor vehicles, factories, and other sources probably increase the risk for lung cancer, and many experts believe that prolonged exposure to polluted air is similar to prolonged exposure to passive smoking in terms of risk for developing lung cancer.
- Asbestos exposure increases the risk of lung cancer by nine times. A combination of asbestos exposure and cigarette smoking raises the risk to as much as 50 times. Another cancer known as mesothelioma (a type of cancer of the pleura or of the lining of the abdominal cavity called the peritoneum) is also strongly associated with exposure to asbestos.
- Lung diseases, such as tuberculosis (TB) and chronic obstructive pulmonary disease (COPD), also create a risk for lung cancer. A person with COPD has a four to six times greater risk of lung cancer even when the effect of cigarette smoking is excluded.
- Radon exposure poses another risk.
o Radon is a by-product of naturally occurring radium, which is a product of uranium.
o Radon is present in indoor and outdoor air.
o The risk for lung cancer increases with significant long-term exposure to radon, although no one knows the exact risk. An estimated 12% of lung cancer deaths are attributable to radon gas, or 15,000 to 22,000 lung cancer-related deaths annually in the U.S. Radon gas is the second leading cause of lung cancer in the U.S. As with asbestos exposure, smoking greatly increases the risk of lung cancer with radon exposure.
o Radon is present in indoor and outdoor air.
o The risk for lung cancer increases with significant long-term exposure to radon, although no one knows the exact risk. An estimated 12% of lung cancer deaths are attributable to radon gas, or 15,000 to 22,000 lung cancer-related deaths annually in the U.S. Radon gas is the second leading cause of lung cancer in the U.S. As with asbestos exposure, smoking greatly increases the risk of lung cancer with radon exposure.
- Certain occupations where exposure to arsenic, chromium, nickel, aromatic hydrocarbons, and ethers occurs may increase the risk of lung cancer.
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