Lung Cancer is one of the most common cancers in the world. The two main types of lung cancer are non-small cell lung cancer and small cell lung cancer. The types are based on the way the cells look under a microscope. Non-small cell lung cancer is much more common than small cell lung cancer.
Cigarette smoking causes most lung cancers. The more cigarettes you smoke per day and the earlier you started smoking, the greater your risk of lung cancer. High levels of pollution, radiation, and asbestos exposure may also increase risk.
Tumors in the lung can be benign (not cancer) or malignant (lung cancer). The malignant tumors:
- May be a threat to life
- Can invade nearby organs and tissues
- Can spread to other parts of the body
- Often can be removed but may grow back
Lung cancer cells can spread by breaking away from a lung tumor. They can travel through blood vessels or lymph vessels to reach other parts of the body. After spreading, cancer cells may attach to other tissues and grow to form new tumors that may damage those tissues.