Most of the cavities in lung cancer are caused by central liquefaction and necrosis, and there will be a series of manifestations in CT examination, and the main signs include bronchial obstruction, uneven thickness of cavity wall, wall nodules, uneven edge and surrounding invasion. 1. Bronchial obstruction: the malignant lesion itself will cause bronchial invasion or compression causing occlusion, and the corresponding bronchial visualization will be interrupted. 2. Uneven thickness of cavity wall: compared with other cavities, lung cancer cavities have uneven thickness, which is mainly related to the proliferation of tumor cells. 3. Wall nodularity: tumor cells grow into the cavity and nodular changes will appear. 4. Uneven edge: the tumor grows outward at an uneven rate, and the edge of the cavity will be uneven. 5. Peripheral invasion: as the tumor grows, it will invade into the surrounding tissues, causing damage to the adjacent tissues. If abnormalities are found in imaging examination, one should seek medical treatment as soon as possible to avoid delaying the condition.