Lung cancer or bronchogenic arcinoma, a life threatening disease, is the uncontrolled growth of abnormal cells in one or both of the lungs. While normal lung tissue cells reproduce and develop into healthy lung tissue, these abnormal cells reproduce rapidly and never grow into normal lung tissue. As a result, lump mass known as a tumor are formed, disrupting the lungs and making it difficult to function properly. Tumors can be benign (non-cancerous) or malignant (cancerous). Benign tumors may grow causing discomfort and bleeding, but they do not spread to other parts of the body and can be removed. Malignant tumors grow aggressively, spread into other areas of the body and destroy normal tissue. The process of spreading the tumor is called metastasis (secondary tumors) and the areas of tumor growth at these distant sites are called metastases.

Usually lung cancer, develops within the wall or epithelium of the bronchial tree. But it can start anywhere in the lungs and affect any part of the respiratory system. Lung cancer mostly affect people between the ages of 55 and 65 and often takes many years to develop. Once it occurs, cancer cells can break away and may spread to the lymph nodes or other tissues in the chest, including the lung opposite to where it originated. It may also spread to other organs of the body, such as the bones, brain or liver.