What is lung cancer?

Lung cancer is a common malignant tumor of the lung. The vast majority of 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 adverse factors, the normal tracheal mucosal epithelium can be overproliferated, which in turn leads to abnormal proliferation. These two lesions are called precancerous lesions. If the adverse factors are alleviated, the precancerous lesions can gradually reverse and become normal cells; on the contrary, if the stimulating factors continue to exist, they can be transformed into early cancer carcinoma in situ, that is, the cancer does not exceed the submucosal layer and continues to develop into invasive cancer. Since early patients have no symptoms, it is usually found that more than 80% are in the late stage.

On the one hand, the cancer spreads along the bronchial wall as it grows and invades the adjacent lung tissue through the bronchial wall to form a mass.

On the other hand, it breaks into the bronchi, causing narrowing or blockage of the tubes. 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; spread to other parts of the body through lymphatic vessels or spread to other lung 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 area of ​​the lung is called peripheral lung cancer.