The diagnosis of lung cancer brings with it many questions and a need for
clear, understandable answers. We hope this National Cancer Institute (NCI)
booklet (NIH Publication No. 99-1553) will help. It provides information about
some causes and ways to prevent lung cancer, and it describes the symptoms,
detection, diagnosis, and treatment of this disease. Having this important
information can make it easier for patients and their families to handle the
challenges they face.
Cancer research has led to progress against
lung cancer — and our knowledge is increasing. Researchers continue to look for
better ways to prevent, detect, diagnose, and treat lung cancer. The Cancer
Information Service and the other NCI resources listed under “National Cancer
Institute Information Resources” can provide the latest, most accurate
information on lung cancer. Publications mentioned in this book and others are
available from the Cancer Information Service at 1-800-4-CANCER. Many NCI
publications are also available on the Internet at the Web sites listed in the
“National Cancer Institute Information Resources” section at the end of this
Words that may be new to readers appear in italics. Definitions of
these and other terms related to lung cancer can be found in the Dictionary. For
some words, a “sounds-like” spelling is also given.
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All types of cancer develop in our cells, the body’s basic unit of life. To
understand cancer, it is helpful to know how normal cells become cancerous.
The body is made up of many types of cells. Normally, cells grow, divide, and
produce more cells as needed to keep the body healthy and functioning properly.
Sometimes, however, the process goes astray — cells keep dividing when new
cells are not needed. The mass of extra cells forms a growth or tumor. Tumors can be benign or malignant.
Benign tumors are not cancer. They often can be removed and, in most
cases, they do not come back. Cells in benign tumors do not spread to other
parts of the body. Most important, benign tumors are rarely a threat to
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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