The following reasons should be considered for breath-holding in lung cancer: a. Large lung cancer tumor leads to obstructive pneumonia or serious lung infection. 2. Lung cancer combined with pleural effusion leads to pleural compression, which affects breathing and causes difficulty in breathing. 3. Lung cancer combined with pericardial effusion can lead to pericardial tamponade and suffocation of breath in severe cases. 4. Complicated pulmonary embolism can also lead to chest tightness and breath-holding symptoms. In conclusion, lung cancer combined with breath-holding is a more serious clinical lesion, and CT examination of lung is needed first to exclude pleural and pericardial effusion and other conditions. If there is pleural effusion or pericardial effusion, puncture and drainage can be done.