Shrinkage after radiotherapy for small cell lung cancer is usually a good thing, because smaller tumors usually mean that the treatment is effective or the condition has improved. Since small cell lung cancer is more malignant and shows lymphatic and blood line metastasis earlier, surgical treatment is not effective in most cases. However, it is very sensitive to radiotherapy and chemotherapy, and in the vast majority of cases, it can achieve the purpose of shrinking the tumor by means of radiotherapy and chemotherapy, and in some cases, it can even achieve the disappearance of the tumor lesions. When it is found that small cell lung cancer shrinks with radiotherapy, patients should continue the treatment course under the guidance of doctors. Since radiotherapy has certain side effects, the single dose is usually not too high, so patients need to undergo radiotherapy for many times, and there is a certain time interval between two times of radiotherapy, which makes the course of treatment longer. Patients should maintain an optimistic mindset and adhere to the treatment program to achieve the expected therapeutic effect.