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| lung cancer |
The cells in the human body have a predetermined pattern of reproduction which involves dividing into multiple cells. This process takes place throughout the life of a person - every minute, there are an estimated ten million cells that divide and reproduce.
The reproduction takes place in a systematic manner and specific kinds of cells required for the body's needs keep being produced. Sometimes however, this orderly process breaks down as far as one or a few cells are concerned. This usually happens because of cell damage.
The damaged cell ends up with a mutation in its DNA structure. At the end of its life cycle, a cell is supposed to mature and die. Instead of doing so, these mutant cells carry on reproducing in an uncontrolled manner. This is basically what cancer is - unchecked reproduction of abnormal cells in specific regions or organs of the body.
One of the worst features of these cancerous cells is that they can find their way into surrounding tissues and organs and also spread to other more distant parts of the body. This process is called metastasis.
With that explanation in place, we are in a better position to find an answer to the question "what is lung cancer".
Lung cancer is an abnormal, malignant growth of cells in a person's lungs. There are many reasons why lung cancer is one of the most dangerous forms of cancer around. A key reason is that lung cancer tends to metastasize or spread to other parts of the body. This happens quite early after the onset of the cancer. For this reason, lung cancer is often not detected until it has spread considerably. This makes it very difficult to treat or control through drugs and radiation.
In addition, lung cancer tends to spread to vital body parts like the liver, adrenal glands, the bones and the brain. This makes the metastasized cancer doubly dangerous.
There is no part of the lung that is immune to cancer. However, the vast majority - about 90% or more - of lung cancers originate in the epithelial lining of the lungs. These linings cover the airways that are responsible for extracting oxygen into the lungs from inhaled air.
That is why lung cancer is also known as bronchogenic carcinoma (meaning, cancer that originates in the bronchia).
Some lung cancers begin in the lining that surrounds the lungs called the pleura. This is a type of cancer called mesothelioma and it is caused by asbestos exposure. They form only a small percentage of all lung cancer cases. Rarer still are cancers that originate in other tissues including blood vessels of the lung.
The two major types of lung cancers are non small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). About four-fifths of all lung cancers are of the non small cell variety.
Small cell lung cancer accounts for only a minority of lung cancers, but is far more dangerous. Cigarette smoking is the main cause of this type of cancer. This type is deadlier because it spreads very fast within the lungs and to other parts of the body.