131I focus-clearing therapy is indicated for DTC metastases (including local lymph node metastases and distant metastases) that cannot be surgically resected but have iodine uptake function. The aim of the treatment is to remove the lesions or partially relieve the disease. The efficacy of DTC treatment is directly related to the degree of 131I uptake by the metastases and the retention time of 131I in the metastases, and is also affected by the age of the patient, the size and location of the metastases, and the radiosensitivity of the metastases to 131I. Younger patients have a greater likelihood of obtaining a cure, and microscopic metastases in soft tissues and lungs are easily cleared; metastases that have formed a substantial mass or bone metastases that are combined with bone destruction tend to be less effective in clearing and treating the lesion, even if the lesion is clearly ingesting 131I. 131I clearance therapy is contraindicated in patients of advanced age, those with other serious diseases, or those who cannot tolerate pre-treatment hypothyroidism. Metastases located in critical areas (e.g., intracranial or paraspinal, intratracheal, paraganglionic metastases, etc.) that are inoperable are not amenable to 131I clearing even if the lesion significantly ingests 131I, and should be managed by other methods.