Lung cancer or bronchogenic cancer is a formation of malignant tumor in one or both lungs due to uncontrolled growth of abnormal cells. Tumor is formed when there is a continuous growth of abnormal cells and when it becomes a mass is called lung cancer tumor.. As a result of forming a tumor in the lung, it inhibits to carry out the normal functions of the lungs (gaseous exchange).A variety of benign and malignant tumors arise in the lung but vast majority are broncogenic carcinomas. The term bronchogenic refers to the origin of these tumors in the bronchial epithelium.
Lung cancer tumors are formed due to DNA mutation in lung tissue cells. Mutation begins through the normal aging process or due to environmental factors such as cigarette smoke, or breathing in asbestos fibers, and to exposure to radon gas. Before a lung cell becomes a cancerous cells it undergoes a series of mutation to form a fully developed cancerous cell. Under precancerous state a lung cell can perform like a normal cell and it loses its function when it becomes a fully developed cancerous cell. When some of the lung cells become fully developed cancerous cells some of the cancerous cell migrate or travel from the lungs to other organs, this process is called metastasis