Bodily Defenses Image Map

Lung Cancer

Overview
Although lung cancer is the leading cause of cancer deaths in the United States, it is also one of the most preventable kinds of cancer. At least four out of five cases are associated with cigarette smoking. More than 170,000 people in the U.S. are diagnosed with lung cancer each year, most between the ages of 40 and 70.  Click here for more statistics.

What causes lung cancer?
Cigarette smoke has 4000 chemicals and of these, over 40 are known to cause cancer. Normal human cells become cancer cells when exposed to carcinogens.
The risk of developing lung cancer in humans is proportional to the number of cigarettes smoked. Smokers are 8-20 times more likely to develop lung cancer compared to people who have never smoked.

For nonsmokers, here is a normal, inflated lung to compare to the smoker's lung below.  This is what your lungs should look like.
The picture on the left is a smoker's lung.  Cigarette smoke has tars and chemical agents in it that irritate the lungs and cause lung cancer to form.  The cancer cells in this picture are shown by the whitish area in an otherwise blackened lung.

Source: American Lung Association

Why is lung cancer a serious problem?
Over 300,000 people die from lung cancer in the United States alone. The economic loss is calculated to be over two billion dollars a year.
Since the majority of lung cancer is diagnosed at a relatively late stage, only 10% of all lung cancer patients are ultimately cured. If the patient cannot be cured by surgery at the time the cancer is found, there is a 50% chance that death will occur in less than one year.

What are the symptoms of lung cancer?
In its early stages, lung cancer normally has no symptoms. Most lung cancers begin to grow silently, without any symptoms. Patients with lung cancer often do not develop symptoms until the cancer is in an advanced stage. The actual time from when one cell becomes cancerous until it is large enough to be diagnosed or produce symptoms may take as long as 10 to 40 years. When symptoms start to appear, they are usually caused by blocked breathing passages or by the spread of cancer to other parts of the body.

Conclusion
Smoking causes cancer.  The occurrence of lung cancer can be reduced by not smoking.

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