Lung cancer, also known as primary bronchial lung cancer, is the most common lung malignant tumor originating from the trachea, bronchial mucosa or glands. According to histopathological characteristics, there are mainly non-small cell carcinoma (including adenocarcinoma and squamous cell carcinoma) and small cell carcinoma. The clinical symptoms of lung cancer are closely related to tumor size, type, stage of development, location, complications and metastasis. Common symptoms include cough, bloody sputum, wheezing, chest pain and so on. There may be no obvious symptoms in the early stage of the disease, and some patients are incidentally found during physical examination.

Dissemination and metastasis of lung cancer

• Direct diffusion

Tumors close to the periphery of the lung can invade the visceral pleura, with cancer cells shedding into the pleural space and forming seeding metastases. The central type or tumor near the mediastinal surface can invade visceral and parietal pleura, chest wall tissue and mediastinal organs.

Hematogenous metastasis

Cancer cells can spread to any part of the body after returning to the left heart with the pulmonary vein. Common sites of metastasis are the liver, brain, lung, skeletal system, adrenal gland, pancreas, and other organs.

Lymphatic metastasis

Lymphatic metastasis is the most common metastatic route in lung cancer. The cancer cells invade the adjacent segmental or lobar peribronchial lymph nodes through the lymph vessels around the bronchi and pulmonary vessels, then reach the hilar or subcarinal lymph nodes, then invade the mediastinal and paratracheal lymph nodes, and finally invade the supraclavicular or cervical lymph nodes.