A prospective study of factors predicting clinically occult spinal cord compression in patients with metastatic prostate carcinoma

BACKGROUND The objective of this study was to identify clinical parameters that predict occult subarachnoid space or spinal cord (SAS/SC) compression, as determined by magnetic resonance imaging (MRI), in patients with metastatic prostate carcinoma. METHODS A prospective study was performed in which 68 patients with bone metastases from prostate carcinoma and a normal neurologic examination underwent MRI of the entire spine after documentation of clinical, X-ray, and bone scan parameters potentially predictive of occult SAS/SC compression. RESULTS Occult SAS/SC compression was diagnosed in 22 patients (32%) using MRI. Nine patients (13%) had compressions at two discontinuous spinal levels. Extensive disease on bone scan, the duration of continuous hormonal therapy prior to study entry, and hemoglobin concentration were found to predict SAS/SC compression by univariate analysis. The extent of disease on bone scan and the duration of continuous hormonal therapy were independent predictors of SAS/SC compression by multivariate analysis (P = 0.02 and P = 0.04, respectively). The risk of occult SAS/SC compression increased from 32% to 44% in patients with a bone scan that showed > 20 metastases as the duration on hormones increased from 0 to 24 months. The risk in patients with fewer metastases increased from 11% to 17% over the same interval. The presence or absence of back pain was not predictive of SAS/SC compression. CONCLUSIONS Patients who are at high risk for occult SAS/SC compression can be identified using clinical parameters and readily available diagnostic tests. These high-risk patients should undergo MRI screening with the aim of diagnosing and treating spinal cord compression before the development of neurologic deficits that may be irreversible. Cancer 2001;92:303–10. © 2001 American Cancer Society.