Your lungs are composed of millions of cells. Every day, thousands of cells die (natural self-cell destruction or apoptosis) to be replaced by new cells. It is a physiological cellular death, genetically programmed, necessary for the proper functioning of your lungs and the entire body. Lung cancer occurs when there is abnormal and anomic cell proliferation in your lungs. The lungs become beset by cells that multiply in an exaggerated manner without committing suicide. During the course of the disease, some cells can migrate from their place of production to form metastases in distant organs.
Major cause of non small cell lung cancer is smoking. Either it is first hand smoke or a second hand smoke (environmental tobacco smoke), cigarette smoke has a carcinogenic effect on your lungs and other organs in your body. That is, you increase your risk of non-small-cell lung cancer every time you smoke or inhale environmental tobacco smoke. It is estimated that nearly 98% of patients with non small cell lung cancer have a smoking history. In addition to tobacco use, you can also become a non-small cell lung victim if you constantly inhale carcinogenic particles: asbestos, radon gas, gasoline, etc.
Once inhaled, toxins contained in tobacco smoke accumulate in the lungs and begin their degenerative effects; those carcinogenic agents can continue their destructive asymptomatically for years in your lungs before causing symptoms. When symptoms finally emerge, the tumor is often already advanced. Approximately 50% of patients with non-small cell lung are diagnosed when the cancer has already spread into parts of the body. There is no cure for extensive-stage small-cell lung cancer; there are therapies that can reduce symptoms and help you live longer. In fact, some patients die within a year of diagnosis.