The most severe threat to mankind is mankind itself; cigarettes, alcohol, and other .
            
man made drugs relate to an enormous percentage of unnatural deaths recorded each .
            
year. One of the most common and most deadly advocates to this is Lung Cancer, which .
            
accounts for one third of all cancer deaths in the United States. Over 90% of lung cancer .
            
patients are smokers, and about 3000 people will die this year due to secondhand .
            
smoking most of who have never smoked a cigarette in his or her lives. .
            
The physical cause of lung cancer is associated with harmful toxins (carcinogens) .
            
in tobacco smoke, exposure to asbestos, radioactive dust, and Radon which damages the .
            
cells in the lungs. Over time these damaged cells could develop into lung cancer. Usually .
            
cilia (tiny hair like projections on cell surfaces) can clean most toxins which are breathed .
            
in, unfortunately smoking eventually overwhelms these structures barring them useless.  .
            
As lung cancer grows, it may spread to the lymph nodes or other tissues in the chest, .
            
including the other lung. Lung cancer is classified in stages that are determined by the .
            
size of the malignant tumor and how far the cancer has spread within the lung, to nearby .
            
tissues, and to other organs. .
            
Like many cancers early detection is the best chance for a full recovery, however .
            
like many cancers the early stages of lung cancer may show no symptoms. In the .
            
advanced stages of lung cancer symptoms become very reveling and persistent. A new .
            
cough or a cough that does not go away, smokers may have a chronic cough from .
            
smoking, but a change in the frequency or severity of their cough may occur. Chest, .
            
shoulder, or back pain that doesn't go away and often is made worse by deep breathing. .
            
At some point, lung cancer will usually spread (metastasize) to other parts of the body . .
            
The most common sites are the bones, the brain, the liver, the other lung, and the adrenal .
            
glands. When lung cancer metastasizes(spreads), the following symptoms may also .