The axial skeleton is the third most common site of metastasis after the lung and liver. The spine has much bone marrow with a rich capillary network, and a vertebral venous plexus that does not pass through the lungs (Batson’s plexus) Most common primaries are breast, lung, prostate, and those of hematopoeitic origin.
Radiotherapy remains the mainstay of treatment.
Who do you operate on?
General indications – neurology, stability, failure of medical management
What about stability?
Taneichi H. Et al. Risk Factors and Probabiliy of Vertebral Body Collapse in metastases of the Thoracic and Lumbar Spine, Spine, 22(3), 239-245, 1997
Attempted to predict vertebral collapse secondary to metastatic disease. Looked at the percentage of tumour occupancy in the body, pedicular involvement, posterior element involvement, and involvement of the costovertebral joint.
In the lumbar spine, the most important factors for collapse were percentage of tumour occupancy and pedicle destruction. Impending collapse was predicted if 35-40% of the vertebral body was involved alone, or if 20-25% of the body was involved with associated involvement of the posterior elements including the pedicles.
In the thoracic spine, the most important factors were costovertebral joint involvement and percentage of tumour occupancy. Impending collapse was predicted if 50-60% of the vertebral body was involved alone, or if 25-30% of the body was involved with associated involvement of the costovertebral joint.
What about life expectancy?
Enkaoua E.A. et al. Vertebral Metastases. A Critical Appreciation of the Preoperative Prognostic Tokuhashi Score in a Series of 71 Cases. Spine. 22(10) 2293-2298, 1997
Attempted to validate Tokuhashi’s scoring prognosticating system in 71 cases – 37 thyroid, 29 renal, 19 unknown primary. The score is composed of six items – general condition, number of extraspinal bone mets, number of vertebral body mets, mets in major internal organs, primary site, and presence of cord involvement. The score is calculated preoperatively, for a maximum possible 12 points.
In patients with a score of seven or less, median survival was only 5.3 months. In those with a score of 8 or more, the median survival was 23.6 months.
Tokuhashi’s Evaluation System
General Condition (Performance Status) Score
Poor (10-40%) 0
Moderate (50-70%) 1
Good (80-100%) 2
Number of extraspinal bone metastatic foci
3 or more 0
Number of metastases in vertebral bodies
3 or more 0
Metastases to major internal organs
No metastases 2
Primary site of the cancer
Lung, stomach 0
Kidney, liver, uterus, other unidentified* 1
Thyroid, prostate, breast, rectum 2
Spinal cord palsy
*Authors felt that unidentified primary portended an extremely poor prognosis and would be better scored a 0 rather than a 1.