Malignant tumors are cancer. Cells in malignant tumors are abnormal
and divide without control or order. These cancer cells can invade and destroy
the tissue around them. Cancer cells can also
break away from a malignant tumor and enter the bloodstream or lymphatic system (the tissues and organs that produce,
store, and carry white blood cells that fight infection and other diseases).
This process, called metastasis, is how cancer
spreads from the original (primary) tumor to form new (secondary) tumors in
other parts of the body.
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The lungs, a pair of sponge-like, cone-shaped organs, are part of the
respiratory system. The right lung has three
sections, called lobes; it is a little larger
than the left lung, which has two lobes. When we breathe in, the lungs take in
oxygen, which our cells need to live and carry out their normal functions. When
we breathe out, the lungs get rid of carbon dioxide, which is a waste product of
the body’s cells.
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Cancers that begin in the lungs are divided into two major types, non-small cell lung cancer and small cell lung cancer, depending on how the cells look
under a microscope. Each type of lung cancer grows and spreads in different ways
and is treated differently.
Nonsmall cell lung cancer is more common than small cell lung cancer,
and it generally grows and spreads more slowly. There are three main types of
non-small cell lung cancer. They are named for the type of cells in which the
cancer develops: squamous cell carcinoma (also
called epidermoid carcinoma), adenocarcinoma, and large cell
Small cell lung cancer, sometimes called oat
cell cancer, is less common than non-small cell lung cancer. This
type of lung cancer grows more quickly and is more likely to spread to other
organs in the body.
|Cancers that begin in the lungs are divided into two major
types, non-small cell lung cancer and small cell lung cancer, depending on how
the cells look under a microscope. Each type of lung cancer grows and spreads in
different ways and is treated differently.
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Lung Cancer: Who’s at
Researchers have discovered several causes of lung cancer — most are related
to the use of tobacco.
- Cigarettes. Smoking cigarettes causes lung cancer. Harmful substances,
called carcinogens, in tobacco damage the
cells in the lungs. Over time, the damaged cells may become cancerous. The
likelihood that a smoker will develop lung cancer is affected by the age at
which smoking began, how long the person has smoked, the number of cigarettes
smoked per day, and how deeply the smoker inhales. Stopping smoking greatly
reduces a person’s risk for developing lung cancer.
- Cigars and Pipes. Cigar and pipe smokers have a higher risk of lung
cancer than nonsmokers. The number of years a person smokes, the number of pipes
or cigars smoked per day, and how deeply the person inhales all affect the risk
of developing lung cancer. Even cigar and pipe smokers who do not inhale are at
increased risk for lung, mouth, and other types of cancer.
- Environmental Tobacco Smoke. The chance of developing lung cancer is
increased by exposure to environmental tobacco smoke (ETS) — the smoke in the
air when someone else smok