Frequency of Screening Magnetic Resonance Imaging to Detect Occult Spinal Cord Compromise and to Prevent Neurological Deficit in Metastatic Castration-resistant Prostate Cancer

Abstract

Aims Neurological deficit from malignant spinal cord compression (SCC) is a major complication of metastatic castration-resistant prostate cancer (CRPC). The aims of the present study were to determine the incidence of neurological deficit in metastatic prostate cancer patients and to determine the optimal frequency of screening magnetic resonance imaging (MRI) spine required to detect clinically occult radiological SCC (rSCC). Materials and methods A retrospective analysis of the clinical data of 130 consecutive patients with CRPC, with no functional neurological deficit, who had screening MRI spine from January 2001 to May 2005, was undertaken. Patients found to have rSCC received radiotherapy. All patients were followed-up to document the incidence of neurological deficit. Results Thirty-seven (28.4%) patients had rSCC on MRI. The proportion of patients free from neurological deficit at 3, 6, 12, 18 and 24 months was 94, 80, 59 and 43%, respectively, in patients who had rSCC on initial MRI and 97.5, 89, 75 and 63%, respectively, in patients who had no rSCC. A high prostate-specific antigen (PSA) level at initial MRI ( P = 0.035) and a short PSA doubling time < 3 months ( P = 0.009) significantly predicted for neurological deficit on univariate analysis, whereas back pain ( P = 0.059), although an important predictive factor, did not attain statistical significance. On multivariate analysis, only rapid PSA doubling time (<3 months) independently predicted for future neurological deficit ( P = 0.042). Conclusion MRI spine can be used to detect asymptomatic rSCC in patients with CRPC and serial estimations are required to maintain a low incidence of clinical SCC. If serial screening MRI spine is used to detect rSCC in 90% of patients before the development of neurological signs, the optimum frequency depends on the subset of patients studied. The results of our study suggest that the optimum frequency would be every 4–6 months for patients with previous SCC, rapid or high PSA or back pain and annually for asymptomatic patients.