Statistics from the United States show that thyroid cancer is the fastest growing solid cancer with an incidence rate increasing by 6.2% per year. Ninety percent of thyroid cancers are differentiated thyroid cancers (papillary and follicular carcinomas), which often metastasize distantly via bloodstream, mostly to lung and bone, with a 10-year survival rate of 90%. Surgery + iodine 131 + TSH suppression therapy is the best mode to ensure good efficacy. The dose of 131I is determined according to the differentiated thyroid cancer (DTC) and the number of bone metastasis sites, with a general dose of 6.48-7.4 GBq (150-200 mci), given orally once, and repeated after 4-6 months. It can be seen that 131I has the ability to specifically affinity to thyroid gland (and cancerous tissue), which can specifically concentrate on the site of metastasis and produce therapeutic effects such as killing cancer cells and controlling further development of cancer cells. Therefore, high-dose 131I can remove residual thyroid tissue in addition to effectively treating metastasis, and it was found that the factors affecting the efficacy are residual thyroid It has been found that the factors affecting the efficacy include the size of the residual thyroid gland, the high iodine uptake rate of the residual thyroid gland, whether there are other functional metastases outside the thyroid gland, etc. The site of bone metastases has a greater relationship. Bone metastases are often of mixed type and can lead to severe bone pain, impaired mobility, spinal cord compression, hypercalcemia and pathological fractures, which can seriously affect the quality of life of patients and can be directly life-threatening. Although 131I treatment alone can alleviate pain and reduce symptoms to a certain extent. However, due to the bone destruction of bone metastases and poor blood flow at the lesions, 131I aggregates less at the lesions and the radiation dose is low, which affects the efficacy. Meanwhile, patients with bone metastases of thyroid cancer often have residual thyroid tissue, which affects the absorbed dose of 131I at the metastases and affects the efficacy. In addition, the special nature of 131I treatment, the interval of re-treatment is up to 4-6 months, which has certain limitations and affects the efficacy rate of bone pain and the quality of survival of patients. The combination therapy of radionuclide 131I combined with zoledronic acid for bone metastasis of thyroid malignancy can complement each other and can provide more extensive and lasting pain relief and better quality of survival. In the combination treatment group, 4 mg of lyophilized zoledronic acid was given 1 week before 131I treatment, dissolved in 100 ml of saline and dripped intravenously for 0.5 h or less (once a month, 6 times in a row as a course of treatment), and oral administration of 131I was given after treatment, and the results showed that the difference between the total effective rate of bone pain in the combination treatment group (91.25%) and the total effective rate of 131I alone (78.58%) The difference was statistically significant (P < 0.05); the difference between the total effective rate of improvement in quality of life in the combined treatment group (90.00%) and the total effective rate of improvement in quality of life in the 131I alone group (71.14%) was statistically significant (P < 0.05). Zoledronic acid is a new generation of highly effective nitrogen-containing diphosphonates, which contains two important nitrogen atoms in the imidazole side chain, and the second nitrogen atom makes its action much stronger than other diphosphonates, which can treat bone metastases well. cell activity (cell proliferation inhibition and cytolysis); inhibition of tumor cell spreading, infiltration and adhesion to the bone matrix; anti-tumor angiogenic effect. Has non-steroidal anti-inflammatory and adrenocorticotropic effects; strong anti-inflammatory inhibitory and analgesic effects by inhibiting prostaglandin production and histamine exertion. It can lower blood calcium, inhibit the destruction of bone by osteoclasts, inhibit bone loss and repair the damaged bone. Therefore, zoledronic acid 4mg is given 1 week before 131I treatment (once a month, 6 times in a row as a course of treatment), which not only controls the spread of tumor cells, but also repairs the damaged bone, improves blood flow at the lesion, which is beneficial to the aggregation of 131I at the lesion, increases the radiation energy at the lesion, improves the sensitivity of the radiation, and improves the effect of bone pain treatment. The treatment of zoledronic acid promotes the improvement of bone metastases, which is beneficial to increase the rate of complete removal of residual thyroid at one time and shorten the time interval and frequency of 131I re-treatment. Also, zoledronic acid can be repeated for 3-4 weeks, which can make up for the treatment gap between 131I re-treatments and improve the quality of life. Zoledronic acid also has the effect of preventing bone metastases from occurring in malignant tumors and reducing the probability of new bone metastases. The study showed that the pain relieving effect, time to effect, and mobility improvement of the combined drug treatment group were significantly higher than those of the control group, and the combined drug could also play a better complementary and additive role, which could effectively improve the patient's physical condition, reduce pain, improve the quality of life, and prevent the occurrence of pathological fractures; the side effects of the combined drug treatment group were mild, and the main adverse effects were the decrease of white blood cell and platelet degree I-II, a few patients experienced transient bone pain The main adverse reactions were the decrease of white blood cell and platelet I-II degree, a few patients showed transient bone pain, a few patients showed slight nausea and vomiting, and the comparison between the treatment group and the control group was basically the same. Therefore, 131I combined with zoledronic acid is a comprehensive and effective treatment for bone metastases of thyroid cancer, which is more effective than 131I alone in treating bone metastases of thyroid cancer and can improve the survival quality of patients more effectively.