Dose‑escalated, short‑course proton radiation for inoperable soft tissue sarcoma

PROSARC-2. Dose-escalated, Hypofractionated, Definitive Proton Radiotherapy for Patients With Inoperable Soft Tissue Sarcoma. A Single-arm, Multicenter, Phase II Clinical Trial.

Phase 2 Interventional Oslo University Hospital · NCT07173972

This will try higher-dose, shorter-course proton radiation to see if it controls tumors better in adults with inoperable soft tissue sarcoma.

Quick facts

PhasePhase 2
Study typeInterventional
Enrollment40 (estimated)
Ages18 Years and up
SexAll
SponsorOslo University Hospital Academic / other
Drugs / interventionschemotherapy, radiation
Locations2 sites (Bergen and 1 other locations)
Trial IDNCT07173972 on ClinicalTrials.gov

What this trial studies

PROSARC-2 is a single-arm, open-label phase II multicenter trial in Norway testing dose-escalated, hypofractionated proton beam therapy for patients with inoperable soft tissue sarcoma. Participants will receive 56 Gy in 16 fractions over four weeks with an optional central tumor boost up to 80 Gy, and will be followed for tumor control and survival outcomes. The trial plans to enroll about 40 patients across major Norwegian sarcoma centers and will collect blood and imaging biomarkers and tumor DNA for translational research. The primary endpoint is 2-year local progression-free survival, with secondary endpoints including overall survival, progression-free survival, and radiologic response.

Who should consider this trial

Good fit: Adults (≥18) with histologically confirmed, measurable inoperable soft tissue sarcoma, ECOG 0–2, able to travel to Bergen or Oslo for proton treatment and able to provide informed consent are eligible.

Not a fit: Patients with operable tumors, poor performance status (ECOG >2), short expected survival, active other malignancies that interfere with safety or follow-up, or inability to travel to the proton centers are unlikely to benefit from this trial.

Why it matters

Potential benefit: If successful, this approach could improve local tumor control while keeping side effects acceptable, potentially reducing the need for additional treatments.

How similar studies have performed: Previous radiotherapy studies suggest dose escalation can improve local control in sarcoma, but hypofractionated proton dose-escalation for inoperable STS remains relatively novel with limited definitive data.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

1. ≥ 18 years of age at the time of informed consent.
2. Histological diagnosis of soft tissue sarcoma including gastrointestinal stromal tumor (GIST).
3. Measurable disease according to RECIST v1.1.
4. Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1 or 2
5. For patients with metastatic disease a life-expectancy greater than 2 years should be expected.
6. Before patient registration, written informed consent must be given according to national and local regulations.
7. Ability to fill in patient questionnaires and comply with study procedures, including travelling to Bergen or Oslo for Proton Beam radiotherapy.

Exclusion Criteria:

1. Patients with a prior or concurrent malignant disease whose natural history or treatment have the potential to interfere with the safety or efficacy assessment of this clinical trial are not eligible. Patients with a history of breast cancer, requiring continued hormonal treatment (e.g. anti-estrogen or an aromatase inhibitor) may be included. Patients with a history of prostate cancer, requiring continued support with luteinizing hormone releasing hormone (LHRH) agonists, with or without androgens, may be included.
2. Previous radiotherapy to the tumor site.
3. Patients with pacemakers and/or implanted defibrillators.
4. Patients not able to give an informed consent or comply with study regulations as deemed by study investigator.
5. Administration of systemic cancer therapy (i.e. chemotherapy, targeted therapy or immune therapy) within 14 days prior to the first fraction of radiotherapy.

Where this trial is running

Bergen and 1 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Soft Tissue SarcomaSoft Tissue Sarcoma AdultSoft Tissue Sarcoma of the Trunk and ExtremitiesSynovial SarcomasUndifferentiated Pleomorphic SarcomaMyxofibrosarcomaLeiomyosarcomaPleomorphic Liposarcoma
Last reviewed 2026-06-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.