The bony skeleton is one of the most common sites of metastatic spread of cancer and is a significant source of morbidity in cancer patients, causing pain and pathologic fracture, impaired ambulatory ability, and poorer quality of life. Animal cancer models of skeletal metastases are essential for better understanding of the molecular pathways behind metastatic spread and local growth and invasion of bone, to enable analysis of host-tumor cell interactions, identify barriers to the metastatic process, and to provide platforms to develop and test novel therapies prior to clinical application in human patients. Thus, the ideal model should be clinically relevant, reproducible and representative of the human condition. This review summarizes the current in vivo animal models used in the study of cancer metastases of the skeleton.

Vertebral pathological fracture and metastatic epidural spinal cord compression (MESCC) due to metastatic cancer inevitably cause pain, neurological deficit, impaired function, and decreased quality of life and are indications for surgery. In such cases, earlier surgical intervention has the potential to prevent permanent neurological deficit and disability and to maintain function and quality of life. Therefore, the aim of this study was to identify and evaluate risk factors for pathological fracture and MESCC in patients with spinal metastases. Retrospective assessment of clinical and radiological parameters was undertaken in patients with spinal metastases. Seventy-two patients with spinal metastases underwent decompressive and/or stabilization surgery for pathological fracture and/or MESCC or nerve root compression. The following items were assessed for association with pathological fracture or MESCC: tumor size, location, type, and morphology; disease burden; pain; and function. Pain, tumor size within the vertebral body, vertebral endplate and 3-column involvement, primary tumor growth rate, and multiple vertebral metastases were associated with increased risk for pathological fracture. Vertebral posterior element and costovertebral joint involvement by tumor, primary tumor growth rate, and the presence of visceral metastases were associated with MESCC or nerve root compression. These factors should be considered in the decision-making process for surgery for spinal metastases. Patients with osteolytic spinal metastatic lesions causing pain, greater than 25% occupancy of the vertebral body, and involvement of the vertebral endplate or all 3 columns should be considered for prophylactic or therapeutic decompressive and stabilization surgery. [Orthopedics. 2018; 41(1):e38-e45.].

Background In patients with spinal metastatic disease, survival prognosis is a key consideration in selection for surgery and determining the extent of treatment. Individual survival prediction however remains difficult. We sought to validate the prognostic accuracy of seven preoperative scoring systems. Methods 61 patients surgically treated for spinal metastases were retrospectively reviewed. Preoperative scores were calculated for Tokuhashi, Revised Tokuhashi, Bauer, Modified Bauer, Sioutos, Tomita, and van der Linden scoring systems. Prognostic value was determined by comparison of predicted and actual survival. Results The Revised Tokuhashi and Modified Bauer scoring systems had the best survival predictive accuracy. Rate of agreement for survival prognosis was the greatest for the Modified Bauer score. There was a significant difference in survival of the prognostic groups for all but the van der Linden score, being most significant for the Revised Tokuhashi, Bauer, Modified Bauer, and Tomita scoring systems (p ≤ 0.001). ConclusionOverall, the scoring systems are accurate at differentiating patients into short-, intermediate-, and long-term survivors. More precise prediction of actual survival is limited and the decision for or against surgery should never be based on survival prognostication alone but should take into account symptoms such as neurological deficit or pain from pathological fracture and instability.