What is the reason for the changes of lung nodules during chemotherapy for lung cancer patients mainly depends on the type of changes, and the main changes include shrinkage and enlargement, which are caused by effective drugs and poor control of drugs respectively. 1. Shrinkage of nodules: the shrinkage of lung nodules during chemotherapy suggests that the application of drugs is effective in controlling the lesions and can be continued. 2. Nodule enlargement: Nodule enlargement is mostly due to drug resistance that has occurred after a long period of time, or the drugs themselves are not appropriate, which suggests that the drugs are not effective in controlling the lesions and need to be adjusted. Nodule changes during chemotherapy need to communicate with the doctor in a timely manner, through the clinical further diagnosis, under the guidance of the clinician for standardized treatment, to avoid causing delays in the condition.