MRI Showing tumor in spine (white arrow) putting pressure on cord (black arrow)
cancer commonly spreads to the spinal vertebrae which can lead to back pain (go here). If the cancer gets more advanced and compresses the spinal cord this lead to neurological symptoms leading to paralysis

See typical CT/MRI in thoracic spine , CT with bone destruction,  MRI severe obstructing cancer, MR T spine

lesion in cervical spine and here, severe lesion in upper spine , severe T spine, and lesion in lumbar spine,

cancer that spreads directly to the spinal cord (rather than the vertebrae) is called intra-medullary metastases and typical MRI pictures are here

more MRI pictures: here and here and here. A CT is not as good as an MRI but a PET scan may show the degree of bone involvement (go here). Cancer in the vertebrae often involved the pedicle (go here)

(see spinal anatomy #1, #2, #3, #4, #5, #6, #7, #8, #9, #10   sites of spread,

and dermatome patterns (# 1, #2, #3, and #4.)

spinal cord syndrome is usually due to cancer spreading to the bone then pushing into the cord (called epidural) but some cancers can spread directly into the cord area (see pic) or directly into the cord itself (see here)