The pathological classification of lung cancer is divided into two types: small cell lung cancer and non-small cell lung cancer: 1. The treatment of small cell lung cancer should be based on systemic chemotherapy, combined with radiotherapy and surgery as the main treatment. Combination therapy is the key to successful treatment of small cell lung cancer. 2.Non-small cell lung cancer Non-small cell lung cancer (NSCLC), about 80% of lung cancer patients belong to this type. The main treatment mode is surgery, combined with postoperative adjuvant radiotherapy. The most common types of NSCLC are as follows: (1) squamous carcinoma, which is the most common among all types of lung cancer, accounting for about 50% of the patients, most of them are above 50 years old, and most of them are men. It is sensitive to radiotherapy and chemotherapy, and metastases firstly through lymphatic metastasis and later through bloodstream metastasis. (2) Adenocarcinoma originates from the mucous glands of bronchial mucosa, and a few of them originate from the mucous glands of large bronchi. Sometimes bloodstream metastasis occurs at an early stage, while lymphatic metastasis occurs later. (3) Alveolar bronchial carcinoma originates from the bronchial mucosa epithelium, also known as alveolar cell carcinoma or adenocarcinoma of the bronchus, which is located around the lung field. Lymphatic and hematologic metastases occur later, but can spread to other lung lobes or invade the pleura via bronchi. The former can be a single nodule or multiple nodules, while the latter has a similar morphology to pneumonia and is more effective when removed surgically. (4) Undifferentiated carcinoma is second only to squamous carcinoma in terms of incidence rate, mostly seen in men, and has a younger age of onset. It usually originates from larger bronchi and is a central type of lung cancer. Undifferentiated carcinoma has high malignancy, rapid growth and early appearance of lymphatic and hematologic metastases, and has the worst prognosis among all types of lung cancer.