According to the survey, nearly 40% of lung cancer patients will have bone metastasis, and once bone metastasis is clearly diagnosed, corresponding drug treatment should be started immediately. There was such a case in the outpatient clinic: Mr. Deng, 58 years old, was diagnosed with middle to late stage lung cancer last year, and received chemotherapy after surgery, and went home to recuperate after the course of treatment. However, last week, when Mr. Deng went back to the cancer hospital for a review and told the doctor about his back pain, the doctor immediately asked him to have a PETECT examination because he suspected that he had bone metastasis of lung cancer. According to the introduction, bone metastasis is one of the most common complications of malignant tumors, and bone metastasis caused by breast cancer, lung cancer, prostate cancer, multiple myeloma and kidney cancer are the most common. Some patients’ bone metastases occur after surgery and radiotherapy and chemotherapy, while some patients, who had no special symptoms before, went to the hospital precisely because of back pain and leg pain, and finally found out that it was bone cancer, and this bone cancer was not the primary lesion, but the bone metastasis occurred from tumors in other parts of the body. This phenomenon happens to lung cancer patients from time to time, and many of them discover lung cancer only because of bone metastasis, and by then, lung cancer has often developed to the middle and late stages. In many elderly people, bone loss becomes more and more serious as they grow older, and they are prone to osteoporosis, which in turn causes back pain and sometimes fractures. For those patients diagnosed with tumors, it is more important to note that bone metastases caused by malignant tumors can cause pathological fractures, spinal cord compression and severe bone pain, which are medically known as “skeletal-related events” (SRE). If people have unexplained fractures and bone pain in daily life, such as fractures without any obvious external factors, or back and leg pain without any cause, they should be alert to the occurrence of osteoporosis, and for cancer patients, the first thing they should suspect is bone metastasis from malignant tumors.