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Vertebral metastases with high risk of symptomatic malignant spinal cord compression.

OBJECTIVE
To find vertebral metastases with high risk of symptomatic malignant spinal cord compression (MSCC), features of vertebral metastases caused motor deficits of the lower extremities were examined.


METHODS
From 2004 through 2006, 78 patients with metastases of the thoracic and/or the cervical spine were treated with radiation therapy (RT). Of these, 86 irradiated lesions in 73 patients were evaluable by magnetic resonance imaging and/or computed tomography at the initiation of RT and were reviewed retrospectively in this study. Twenty-eight patients (38%) had motor deficits at the initiation of RT. Assessed factors were age, sex, primary disease (lung, breast, digestive system and other cancer), lamina involvement, main level of tumor location and vertebral-body involvement.


RESULTS
Incidence of motor deficits at the initiation of RT was 55% for lesions with lamina involvement and 5% for lesions without lamina involvement (P < 0.0001). Incidence of motor deficits was 15% for lesions located mainly in the cervical spine and/or the upper thoracic spine (Th1-4), 54% for lesions located mainly in the middle thoracic spine (MTS) (Th5-8) and 30% for lesions located mainly in the lower thoracic spine (Th9-12) (P = 0.0095). Age, sex, primary disease and vertebral-body involvement were not statistically significant factors for incidence of motor deficits due to MSCC (P > 0.9999, P = 0.7798, P = 0.1702 and P = 0.366, respectively).


CONCLUSIONS
Vertebral metastases with lamina involvement tended to cause symptomatic MSCC. Latent development of MSCC occurred more frequently in the MTS compared with other levels of the thoracic and the cervical spine.