Lung Cancer Health Center
Non-Small-Cell Lung Cancer
Non–Small-Cell Lung Cancer Overview
Cancers are diseases in which normal cells transform so that they grow and
multiply without normal controls. In many types of cancer, this results in the
growth of one or more large masses, or tumors, of these transformed cells. This
can happen in almost any part of the body. When it happens in the lungs, the
disease is called lung cancer.
Lung cancer is one of the most common types of cancer; this is because the
lungs are exposed to the external environment more than most other organs are.
In many cases, cancer-causing substances (carcinogens) in the air are inhaled
and cause cell damage that later becomes cancer. The most common cause of lung
cancer, by far, is smoking.
Two main types of lung cancer exist: small cell lung cancer and non–small-cell
lung cancer. Non–small-cell lung cancer is a catchall term for all lung cancers
that are not small-cell type. They are grouped together because the treatment
is the same for all non–small-cell types. Together, non–small-cell lung
cancers, or NSCLCs, make up about 75% of all lung cancers. Each type is named
for the types of cells that were transformed to become cancer. The following
are the 3 most common types of NSCLC in the United States:
- Adenocarcinoma/bronchoalveolar – 35-40%
- Squamous cell carcinoma – 25-30%
- Large-cell carcinoma – 10-15%
Like all cancers, lung cancer is most easily and successfully treated if it is caught early. An early-stage cancer is less likely to have grown to a large size or to have spread to other parts of the body (metastasized). Large or metastasized cancers are much more difficult to treat.
Non–Small-Cell Lung Cancer Causes
Tobacco smoking
- Tobacco smoking is the cause of lung cancer in as many as 90% of
cases.
- A person who smokes is 13.3 times as likely to develop lung cancer as is a
person who has never smoked. The risk also varies with the number of cigarettes
smoked per day; people who smoke more than 20 cigarettes per day have a much
greater risk of developing lung cancer than do those who smoke fewer than 20
cigarettes per day.
- Once a person quits smoking, the risk of lung cancer increases for the
first 2 years and then gradually decreases, but the risk never returns to the
same level as that of a person who has never smoked.
- Not all people who smoke develop lung cancer, and not all people with lung cancer smoke. Clearly, other factors, including genetic predisposition, also play a role.
Passive smoking (secondhand smoke)
- As many as 15% of lung cancer cases involving nonsmokers may be caused by
secondhand smoke.
- The Environmental Protection Agency has recognized passive smoking as a potential cause of cancer.
WebMD Medical Reference from eMedicineHealth
