What is lung cancer

What is lung cancer?

Lung cancer is a common lung malignancy. Most lung cancers originate from the bronchial mucosal epithelium, so it is also called bronchial lung cancer. However, a few cancers originate from the alveolar epithelium or bronchial glands. Due to the influence of various unfavorable factors, it can cause excessive proliferation of normal tracheal mucosal epithelium and then cause abnormal proliferation. These two lesions are called precancerous lesions.

If the adverse factors are eliminated, precancerous lesions can gradually reverse and become normal cells; on the contrary, if the stimulating factors continue to exist, it can be transformed into early cancer in situ, that is, the cancer does not exceed the submucosal layer and continues to develop into invasive cancer. Since early patients are asymptomatic, more than % of them are generally found in the late stage at the age of 80. During the growth process, cancer extends along the bronchial wall, invades the adjacent lung tissue through the bronchial wall to form a mass, and on the other hand, it breaks into the bronchus, causing stenosis or blockage of the bronchi. The further development and spread of cancer can spread directly from the lungs to the chest wall, mediastinum, heart, large blood vessels and other adjacent organs and tissues; transfer to other parts of the body through the lymphatic and blood vessels, or spread to other lobes through the respiratory tract.

The growth rate and spread of cancer depend on the tissue type, degree of differentiation and other biological characteristics of the cancer. Distribution of lung cancer: more in the right lung than in the left lung, and more in the lower lobe than in the upper lobe. Lung cancer originating from the main bronchi and lobar bronchi is called central lung cancer; lung cancer originating from the distal bronchus and the peripheral areas of the lungs is called peripheral lung cancer.