Metastatic bone tumors refer to malignant tumors that originate in organs or tissues outside the bone, spread to the skeleton via hematogenous or lymphatic pathways, and continue to grow, forming secondary lesions. These tumors are commonly observed in middle-aged and elderly patients, with a predominance in those aged 40 to 60 years. In children, metastatic bone tumors typically arise from neuroblastomas. The most frequently affected sites are bones of the axial skeleton, and cancers prone to bone metastasis include breast cancer, prostate cancer, lung cancer, and kidney cancer, among others.
Clinical Features
The main symptoms include pain, swelling, pathological fractures, and spinal cord compression, with pain being the most common. X-ray imaging may reveal osteolytic lesions (e.g., in thyroid cancer and renal cancer), osteoblastic lesions (e.g., in prostate cancer), or mixed patterns of bone destruction, with osteolytic lesions being the most prevalent. Pathological fractures are also often observed. Radionuclide bone scans are considered a sensitive method for detecting metastatic bone tumors.
Laboratory Findings
Elevated blood calcium levels are observed in osteolytic bone metastases, while increased serum alkaline phosphatase levels are associated with osteoblastic bone metastases. Elevated acid phosphatase levels are frequently seen in cases of prostate cancer with bone metastases.
Treatment
The management of metastatic bone tumors generally involves palliative therapy. A proactive approach is taken with the goals of extending survival, alleviating symptoms, and improving quality of life. Comprehensive treatment targeting both the primary cancer and metastatic lesions is typically employed, and the outcomes largely depend on the site of the primary tumor and the extent of the disease.