What is the average life expectancy of someone with stage iii or iv spinal cancer?

More info needed.: Most likely it's not "spinal cancer", which would be a cancer that started in the spine, but a cancer from somewhere else that has spread (metastasized) TO the spine. If so, it's still the cancer of where it started (bone or breast or prostate, etc.). Also, stage III vs. stage IV have different enough treatment and prognosis that they should be considered separately; worth learning this detail).