Radiology

Retrospective cohort study

Proton therapy

Chordoma

Nuclear medicine

Surgery

Sacrum

Lumbar

Radiation therapy

Medicine

Radiotherapy and Oncology

Chordomas are rare primary bone tumors with an incidence of 0.1 for every 100,000 individuals and prevalence of less than one for every 100,000 [1]. They account for 1–4% of primary malignant bone tumors and 17% of all primary bone tumors of the spine [2,3]. These tumors are thought to arise from embryonic remnants of the notochord along the axial skeleton. Normally the human notochord disappears at approximately 8 weeks of fetal development, but in some individuals the notochord does not fully degrade, and the prevailing theory is that these remnants can develop into a chordoma.

Definitive high-dose, proton-based radiation for unresected mobile spine and sacral chordomas