Lung is the respiratory organ of human body, which consists of trachea, bronchi at all levels and alveoli. Malignant tumors occurring in bronchi, and alveolar epithelial cells are called lung cancer. Clinically, according to the location of tumor growth, there are central type lung cancer and peripheral type lung cancer. Those occurring above grade 3 bronchi are called central lung cancer, while those occurring below grade 4 bronchi are called peripheral lung cancer. Lung cancer is one of the most threatening malignant tumors to the health and lives of occupational groups in the world today. Worldwide, by 1999, there were 1 million new cases each year, the highest mortality rate among men from tumors. In many countries, the incidence of lung cancer is still on the rise. The incidence of lung cancer in China is increasing at a rate of 4.5% per year. The recent increase in the incidence of lung cancer in women has been associated with an increase in smoking and passive smoking in women and air pollution in small kitchen environments. It is predicted that the most common diseases in the early 21st century are likely to be lung cancer and AIDS.