Human being has two lungs, one at left and the other one at right. They are located on the diaphragm and protected by the ribcage. The left lung is divided into two lobes; the right lung has three lobes, which makes it larger and heavier. All these lung tissues are formed by a group of cells that allow the exchange of vital gases, oxygen and carbon dioxide. At every moment, thousands of cells naturally die to be replaced by new healthy cells. Lung cancer occurs when a group of cells refuses to die and begin to multiply uncontrollably to form malignant growth in the tissue of the lungs.
Smoking is the leading cause of small cell lung cancer. It is responsible for about 90% of lung cancers among men and 78% among women. It is estimated that nearly 98% of small cell lung cancer patients have a smoking history. In addition to direct use of tobacco, being frequently exposed to secondhand smoke or carcinogenic particles in the air – asbestos, radon gas, gasoline, etc. – can also cause small cell lung cancer.
Once inhaled, toxins contained in tobacco smoke (including secondhand smoke or passive smoke) accumulate in the lungs and begin their degenerative effects, slowly and sometimes asymptomatically. When symptoms finally emerge, the tumor is already very advanced. Approximately 65-70% of patients with small cell lung cancer have an extensive malignant tumor at diagnosis. In general, extensive-stage small-cell lung cancers are incurable; they kill their victims within 12 months after diagnosis.