Patients with advanced cancer especially with bone metastasis to spine, should be aware of any acute severe spinal pain which may or may not be associated with loss of sensation / power in the limbs.
The patient should visit the hospital / specialist immediately. This may herald compression of spinal cord by cancer and hence immediate treatment would require to either stop/ reverse the impending paralysis. The other issues, albeit not an emergency, includes worsening of urinary symptoms, blockage to ureters (tubes that drain the kidney), and blockage to bowel. The above may require surgical intervention. Hence discuss with your doctor about the management options.