APIS · Pelvic / Sacral Sarcoma
Unresectable Pelvic or Sacral Sarcoma
Proton or carbon-ion therapy may be relevant for pelvic or sacral sarcoma when complete surgery is not possible or would cause major loss of function. The pathology subtype, previous treatment and the radiation dose that nearby bowel, bladder and nerves can tolerate determine the options.
Surgery and Function
A sarcoma surgical team should review whether the tumor can be removed and what that would mean for walking, bladder or bowel function, and nerve function. “Unresectable” means surgery cannot remove the tumor safely or completely; it does not mean every treatment is ruled out. [1][2]
Radiation may treat an unresectable tumor, remaining cancer after surgery, or a local recurrence. The place of chemotherapy depends on the sarcoma subtype.
Sarcoma Subtype Matters
Chordoma
Chordoma often arises in the sacrum or spine and can require a high radiation dose. Proton and carbon-ion therapy have disease-specific evidence, particularly when complete surgery is difficult. [1][3]
Chondrosarcoma
Location, grade and subtype affect the treatment. Surgery remains central when possible; particle therapy can be relevant in some difficult axial tumors. Chondrosarcoma should not be treated as though it were chordoma. [1]
Other bone and soft-tissue sarcomas
These include biologically different cancers. Some rely heavily on systemic treatment; others raise a difficult local-treatment problem. Chordoma results cannot be applied to all sarcomas. [1][2]
Proton and Carbon-Ion Treatment
A proton plan may reduce dose to nearby bowel, bladder or nerves. Carbon ions also have a higher biological effect, which can matter for some tumors resistant to conventional radiation. Neither can make an unsafe radiation plan safe simply by changing the beam type.
The hospital reviews pathology subtype, tumor size, previous surgery, implants, previous radiation and the tumor’s relationship to nearby organs. Implants can also affect imaging and dose planning.
Evidence by Sarcoma Subtype
Use evidence for the exact diagnosis and treatment setting. Most published carbon-ion sarcoma studies are observational.
| Study | Reported outcome | What it means |
|---|---|---|
| Sacral chordoma: Demizu et al., 2021; 219 patients [4] | 5-year local control: 72%; grade 3 or higher late toxicity: 6%. | Japanese retrospective multicenter study. This is chordoma evidence, not an estimate for every sarcoma. |
| Unresectable soft-tissue sarcoma: Li et al., 2026; 48 patients [5] | 5-year local control: 60.3%. | Mixed subtypes and primary/recurrent disease; 9 patients had previous radiation. Small observational cohort. |
Local control describes the treated tumor, not the risk of distant spread. Treatment risks can include bowel or bladder injury, nerve damage, fracture and soft-tissue injury, depending on the location and prior treatment. [1][3]
Required Records for Hospital Review
If the area was irradiated before, the earlier radiation dose and plan need review.
Helpful later additions include the exact pathology subtype, pelvic or sacral MRI, previous operation reports and implant details.
General records and submission guidance. Korean hospital programs.
Treatment and Travel Planning
Ask how pain, walking, sitting, bowel or bladder problems and daily support will be managed. The hospital confirms whether positioning for treatment is possible and whether inpatient care or a caregiver is needed.
The number of sessions and total stay depend on the tumor and plan. Review planning time, treatment costs and accommodation.
Explore Review for Sarcoma
Clarify the pathology subtype and the surgical or functional problem you want reviewed.
Sources and dates
- Gerrand et al. UK guidelines for the management of bone sarcomas. British Journal of Cancer, online 2024; issue 2025. doi:10.1038/s41416-024-02868-4.
- Hayes et al. UK guidelines for the management of soft tissue sarcomas. British Journal of Cancer, online 2024; issue 2025. doi:10.1038/s41416-024-02674-y.
- Carbon Ion and Proton Therapy in Sacral Chordoma: A Systematic Review (2025). Observational evidence and reported complications; comparative conclusions require caution.
- Demizu et al. Carbon ion radiotherapy for sacral chordoma: a retrospective nationwide multicentre study in Japan. Radiotherapy and Oncology, 2021. doi:10.1016/j.radonc.2020.09.018.
- Li et al. Carbon ion radiotherapy for unresectable primary or recurrent soft tissue sarcomas: long-term outcomes based on the local effect model. BMC Cancer, 2026. doi:10.1186/s12885-026-16213-w.
- Yonsei Cancer Center, official program update, August 19, 2026.
Content reviewed October 23, 2026.