Spot-Scanning-Based Proton Therapy for Extracranial Chordoma

Particle therapy using carbon ions or protons as a definitive therapy for patients with primary sacral chordoma

“…Proton treatment was selected in this patient in terms of the skin dose. significant differences were found between the 16-and 32-fraction protocols in both BED 10 …”

“…[1][2][3][4][5] They constitute 1-4% of all primary malignant bone tumours, and sacral chordomas account for .50% of all chordomas. 1,2,6 Chordomas grow slowly [1][2][3] and show fewer metastases than other bone and soft-tissue tumours, 4,[7][8][9][10] and mortality is almost invariably because of local disease progression. 4,9 These tumours are difficult to treat because they tend to progress extensively to anatomical locations in proximity to the sacral nerve plexus, cauda equina and bowel and because the sacrum is important for the patient's mobility.…”

“…4,6,8,[11][12][13][14][15][16][17][18][19] However, complete resection is rarely possible because tumours grow to large sizes before symptoms appear. 4,7,20 Thus, regardless of the low-grade malignancy, LC is poor 8,10,13,17 and chordomas show low sensitivity to chemotherapy 1,2,4,6,13,16,17,21 and conventional photon radiotherapy. 4,6,10,19 Particle therapy, such as carbon ion therapy (CIT) and proton therapy (PT), can deliver high-dose radiation to tumours while minimizing the dose delivered to organs at risk because of its precise dose distribution compared with conventional photon therapy.…”

“…4,7,20 Thus, regardless of the low-grade malignancy, LC is poor 8,10,13,17 and chordomas show low sensitivity to chemotherapy 1,2,4,6,13,16,17,21 and conventional photon radiotherapy. 4,6,10,19 Particle therapy, such as carbon ion therapy (CIT) and proton therapy (PT), can deliver high-dose radiation to tumours while minimizing the dose delivered to organs at risk because of its precise dose distribution compared with conventional photon therapy. [22][23][24][25][26][27][28][29][30][31][32] Particle beams possess a physical characteristic called the Bragg peak, which emits a relatively low dose near the body surface and releases the maximum energy just before it stops in the depth.…”

“…7,16,20 Some reports demonstrating the usefulness of PT for sacral chordomas have also been published. 10,[33][34][35] The Hyogo Ion Beam Medical Center (HIBMC) is the world's first institution capable of applying both CIT and PT, and we have treated sacral chordoma patients with both types of ion beam therapy for years. In this study, we retrospectively evaluated the efficacy and toxicity of particle therapy using carbon ions or protons for primary sacral chordomas at HIBMC.…”