Lung squamous carcinoma is more malignant compared to adenocarcinoma. The doubling time of lung squamous carcinoma cells is 75-90 days, which means it takes 2.5-3 months for the number of lung squamous carcinoma cells to double. Compared to adenocarcinoma of the lung, squamous lung cancer has more chances to obtain surgical resection because it progresses relatively slowly and metastasizes relatively late, but squamous lung cancer is less sensitive to radiotherapy and chemotherapy than adenocarcinoma, and there are fewer effective chemotherapy drugs and regimens. Although the doubling time of adenocarcinoma is the slowest among the four common pathological types of lung cancer, and most lung adenocarcinoma lesions seen clinically are relatively small, lung adenocarcinoma cells have a high metastatic characteristic and often have metastasized in multiple locations throughout the body when the lung is still a very small lesion, which is often referred to as small adenocarcinoma and large metastasis in clinical practice.