Chordomas: are a very rare, slow growing type of bone cancer. Chordomas develop from the notochord, which forms the early spinal tissue in a baby developing in the womb. Chordoma is a rare slow-growing neoplasm thought to arise from cellular remnants of the notochord. The evidence for this is the location of the tumors. Related Journal: Journal of American academy of orthopaedic surgeons, Journal of Neurological Surgery, Journal of Neuro Surgery