The prognosis of low-grade malignant tumors is generally better after surgery, and most patients can achieve clinical cure, i.e., life expectancy is more than 5 years, but a small number of patients may recur or even metastasize, and their life expectancy is shorter than 5 years. For low malignant tumors such as papillary thyroid tumor, after surgery with nuclear iodine-131 treatment, usually the 5-year survival rate can reach more than 90%, and even some patients can reach clinical cure. However, a small number of patients may recur 1~2 years after surgery due to genetic, environmental and other factors. Low-grade malignant tumors are malignant after all, and patients must go to the hospital regularly for review or physical examination after surgery; patients may still have recurrence or even metastasis after surgery, only with a lower likelihood of occurrence.