[Particle beam radiotherapy with a surgical spacer placement for unresectable sacral chordoma].

Sacral chordomas constitute more than half of all chordomas and have a slower local growth than other bone malignant tumors. Although complete radical resection produces a longer local control and disease-free survival at the initial visit, chordomas are already often too large for complete resection to be possible. Particle radiotherapy consisting of proton and carbon-ion is a promising new modality which has an inherent anti-tumor effect against many types of malignancies. However, the application of particle radiotherapy for tumors adjacent to the gastrointestinal tract like sacral chordoma is restricted because the tolerance dose of the intestine is extremely low. A novel two-step treatment was developed with surgical spacer placement and subsequent proton radiotherapy to administer particle radiotherapy with curative intent. This report presents a case of a patient with a huge sacral chordoma treated by this method. This new strategy may potentially be an innovative and standard therapy for unresectable sacral chordoma in the near future.