There are a number of treatments now available to patients with metastatic castrate-resistant prostate cancer (mCRPC). However, the optimal timing and order in which they are given is less clear. Radium-223 was FDA-approved for mCRPC patients with symptomatic bone metastases and no visceral metastases. This was based on the results of the ALSYMPCA trial, whose patient cohort had limited exposure to abiretarone, enzalutamide and to a degree docetaxel. This study assessed 41 mCRPC patients who had already received one or more mCRPC treatments and the impact radium-223 had on spinal epidural disease (diagnosed by MRI). The results show that in patients with spinal epidural disease (who are at risk of spinal cord compression), there was a high rate of progression to spinal cord compression and cessation of radium-223 treatment. This would suggest that the benefit suggested by the ALSYMPCA trial may be less pronounced in a heavily pre-treated cohort. The authors highlight the need for studies to determine the optimal timing of radium-223 in the context of other mCRPC therapies.