According to research, the incidence of bone metastasis of certain malignant tumors is very high, for example, the incidence of bone metastasis of breast cancer, prostate cancer, lung cancer is as high as 50~85%, while other cancers such as nasopharyngeal cancer, esophageal cancer, bladder cancer, renal cancer, uterine cervix cancer, pancreatic cancer and so on, may all have bone metastasis. Bone metastasis often causes severe pain, bone fracture, bone marrow failure, difficulty in walking and nerve compression symptoms. Bone pain is the most prominent symptom of many patients, which is the result of tumor invasion to the periosteum with rich innervation, and can also be caused by the thinning of bone tissues due to the mechanical compression of the tumor as well as the spreading of the tumor from the bone to the nerve tissues. The stimulation of nerve endings by chemicals released from the destruction of bone tissue is also an important cause of bone pain. As a result of this severe bone pain, patients suffer a lot and their quality of life is seriously reduced. There are two treatment goals for bone metastatic cancer: one is to stop pain; the other is to eliminate and reduce the lesions. Only by eliminating and reducing the lesions can the purpose of pain relief be achieved fundamentally. At present, the commonly used treatment methods include surgery, external radiotherapy, chemotherapy and the application of various painkillers. These treatments have their clinical value for patients with different sites and different clinical stages, but they all have certain limitations and shortcomings. For example, surgery and radiotherapy are often powerless to treat extensive bone metastases; chemotherapy has heavy systemic toxic side effects; and some painkillers are addictive. At present, medical experts at home and abroad are researching and searching for new and effective treatment methods. Radionuclide therapy is one of the important results of such research. It mainly includes two methods, 89Sr therapy and 153Sm-EDTMP therapy. The indications of radionuclide therapy are: 1. Clear diagnosis of bone metastatic cancer, especially those with extensive bone metastases. 2. Radionuclide bone imaging can see obvious radioactive uptake in bone metastases, so bone imaging is necessary preparation before treatment. 3. If severe bone pain is caused by bone metastasis and chemotherapy and radiotherapy are ineffective, and some patients have bone metastasis but have no pain, radionuclide treatment can prevent the pain. 4. Leukocyte＞3.0×109/L, platelet＞80×109/L. 89Sr (89 strontium) treatment for bone metastatic cancer 89Sr is a pure beta-emitting radionuclide, which was used in the treatment of bone metastatic cancer in 1942, and it is an early used bone therapy drug. Strontium belongs to the same group as calcium in the periodic table of elements, and its metabolism is similar to that of calcium, which is mainly concentrated in the skeletal system and less distributed in other tissues and organs of the body. When 89Sr is injected intravenously into the body, 90% of it is concentrated in the skeletal system, and only 10% of it is excreted by the kidneys, and the amount of 89Sr in the bone metastases is 2-25 times of that in the normal bone, which is a very good analgesic for the pain caused by bone cancer. The half-life of 89Sr is relatively long, up to 50.5 days, and it is quickly taken up by the bone after injection. The biological half-life in the metastatic foci is >50 days, and the biological half-life in the normal bone is 14 days, and the 89Sr in the metastatic foci has a long residence time, which may be due to the recirculation of 89Sr released from the normal bone. At 90 days after injection, the amount of 89Sr in the metastatic foci can still reach 20%~88%, which can maintain the long-lasting effect of the drug, up to one year. 89Sr treatment cycle is every three or six months treatment. In some patients, regular follow-up bone imaging showed that with the prolongation of time after 89Sr injection, the abnormally concentrated shadow was shrinking, fading, or even disappearing, and the clinical symptoms also improved significantly. 89Sr can also reduce the level of alkaline phosphatase and prostaglandin (PEG), which is conducive to reducing osteolysis, repairing bone, and achieving the purpose of pain relief and lowering blood calcium. The main therapeutic role of 89Sr is analgesia to improve the quality of life of patients and reduce pain. It is reported that 79%~92% of prostate cancer and breast cancer patients have pain relief and improved quality of life after 89Sr treatment. At present, most scholars believe that 89Sr has the best efficacy on bone metastasis caused by these two cancers, with the total effective rate of 80%~90%, and 10%~18% of patients’ pain completely disappeared. 89Sr has also been used in the treatment of bone metastasis pain caused by lung cancer, renal cancer, nasopharyngeal carcinoma and other carcinomas. Another purpose of 89Sr treatment is to make the bone metastasis foci shrink or disappear in order to alleviate the condition and prolong the patients’ life. Its b-rays can kill tumor cells, thus in addition to analgesia, 89Sr can also play a therapeutic role in bone metastases. At present, some scholars use 89Sr for the treatment of bone metastases not accompanied by pain in order to prevent and delay the occurrence of bone pain. 153Sm (153 samarium)-EDTMP for bone metastatic cancer 153Sm- EDTMP (ethylenediamine tetramethylene tetrazolium phosphonate), commonly known as a biological missile for treating bone tumors, is also known as radionuclide therapy for bone cancer. The drug has high affinity to bones, especially bone tumor sites after intravenous injection, the drug concentration in bone is 4,000 times larger than that in muscle, and the drug concentration in lesion bone is 18~32 times larger than that in normal bone, therefore, it can inhibit the growth of tumor cells by using the b-rays released by radionuclide 153Sm to stop the development of lesions, and then cause the degeneration and death of tumor cells, so as to achieve the therapeutic purpose of both relieving pain, and eliminating and decreasing the lesions. This can achieve the therapeutic purpose of both pain relief and elimination and reduction of lesions. Advantages of 153Sm-EDTMP treatment: 1. Simple treatment method: one course of treatment only requires one intravenous injection, and the treatment can be repeated in half a month to one month depending on the situation, and there is generally no serious discomfort. 2. 2. Good pain relief effect: according to the internationally recognized classification of cancer pain and the World Health Organization’s standard of judging the efficacy of cancer, the total effective rate of 153Sm on bone cancer pain relief reaches 93%. Generally, bone pain disappears or is obviously reduced in 2~7 days after injection, and can be maintained for 1~6 months. 3. It has the effect of eliminating and reducing the size of bone metastatic cancer: according to the statistics, its elimination and reduction rate is about 30%. 4. No obvious damage to important organs; because 153Sm is basically completely cleared from the blood 1 hour after injection, except more than 50% of it reaches the bones and lesions to play a therapeutic role, the rest of it is rapidly discharged from the urine, so it will not cause damage to other organs and tissues. 5. No serious myelosuppressive effect: according to the data of our hospital, 153Sm who did not receive other treatment or only received radiotherapy before treatment, there is no significant difference in blood picture before and after treatment, and a few patients have platelet and white blood cell lowering, but generally can be recovered within a short period of time. It is important to note that any malignant tumor is not a localized disease but is systemic. The complexity and systemic nature of malignant tumors determines the multidisciplinary nature of treatment. In addition to surgery, radiotherapy and chemotherapy, there are immunotherapy, endocrine therapy, traditional Chinese medicine, fever therapy, laser therapy, interventional therapy and so on, which have their own indications, advantages and disadvantages. Radionuclide therapy, if scientifically arranged and comprehensively applied together with other therapeutic methods, will surely achieve better therapeutic effect.