Purely osteolytic metastases are generally from lung, kidney, thyroid, or colon cancer. Metastatic bone tumors from kidney or thyroid carcinoma are usually hypervascular, and preoperative embolization should be considered. Osteoblastic metastases are most often seen with prostate or breast carcinoma. The primary tumor sometimes may not be known, but it can usually be detected with CT scans of the chest and abdomen. In patients with a history of carcinoma, the presence of a solitary tumor necessitates a search for other sites of skeletal involvement. If there is no history of carcinoma and staging studies do not reveal a primary carcinoma, a needle biopsy is frequently performed to assess the isolated lesion. Even with no known primary tumor, an isolated lesion in someone older than 40 is usually a metastasis and less likely myeloma or lymphoma. Primary sarcomas in patients older than 40 are much less likely than metastatic disease, myeloma, or lymphoma. For multiple metastatic lesions, chemotherapy, hormonal manipulation, and palliative radiation therapy are therapeutic options. Surgery is performed for most pathologic fractures and for some pathologic lesions that are believed to have high likelihood of fracture (impending fractures), such as those with over half of the diameter of the bone destroyed or with bone cortical destruction over 3 cm in length. Prognosis for patients with skeletal metastases is poor, although patients with isolated bone metastases particularly with breast cancer and renal cell cancer can live for a number of years.