Carbon Ion and Proton Therapy in Sacral Chordoma: A Systematic Review

Abstract

Background: chordomas are characterized as locally aggressive yet infrequently metastasizing malignant neoplasms of bone, primarily arising in the axial skeleton, with a notable prevalence in the sacral region. En bloc resection is recognized as the standard treatment for sacral chordoma; however, its feasibility is not universally guaranteed. Therefore, definitive proton, carbon ion, or photon therapy is often utilized as an alternative to surgical intervention or as a (neo-)adjuvant measure in conjunction with surgery, owing to their role in enhancing local control. Methods: a search of PubMed yielded 127 articles, with 18 that were ultimately included in the review. This review aims to systematically evaluate clinical outcomes and complications associated with hadron therapy in cases of sacral chordomas. The review followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, including publication dates up to January 2025. Results: data extraction showed promising outcomes for patients treated with hadron therapy alone or when hadron therapy was used as an adjuvant for surgery, even if complications are described. The 5-year overall survival estimated from evaluating 10 of 18 articles was 82.4%, although some articles reported different results in shorter follow-up periods. Skin ulceration and pain were described in 323 (29%) and 186 (16%) patients, respectively. Chronic complications reported were sacral fractures, metastasis, rectal disorders, urinary disorders, and peripheral motor and sensory neuropathy. Conclusions: hadron therapy represents a highly effective and promising treatment for sacral chordomas. In cases of inoperable tumors, it has demonstrated outcomes comparable to surgery while significantly reducing treatment-related morbidity. Hadron therapy is also viable as adjuvant therapy and provides superior outcomes for patients who undergo surgery with positive margins compared to those treated with surgery alone, improving local control and overall prognosis.

Keywords: carbon ion therapy; chordoma; hadron therapy; proton therapy; sacrum.

Figure 1

PRISMA flowchart.