A Phase 2 interventional study of Definitive radiotherapy in Soft Tissue Sarcoma (STS), Soft Tissue Sarcoma Adult and Soft Tissue Sarcoma of the Trunk and Extremities, sponsored by Oslo University Hospital. Recruiting at 2 sites in Norway. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-01-28.
Sponsored by Oslo University Hospital · Phase 2, Interventional, and Treatment
The purpose of the study is to study if dose escalated proton radiotherapy can improve local controll for patients with inoperable soft tissue sarcomas. The standard treatment is photon-based radiation. By using proton radiotherapy instead, the hypothesis is that the dose can be increased to enhance treatment effectiveness without increasing side effects.
The planned radiation dose is 56 Gy in 16 fractions (treatments) over 4 weeks (4 fractions per week), with a maximum dose escalation centrally in the tumor up to 80 Gy (5 Gy per fraction).
At the same time, the study will investigate biomarkers that can predict treatment response, including changes in the tumor's genetic material (DNA), measurements of various molecules in the bloodstream, and the tumor's appearance on MRI scans.
The primary endpoint is local control after 2 years, meaning that the treated tumor has not grown during this period. Secondary endpoints include overall survival, progression-free survival, radiological response rates, side effects, and quality of life.
The study will be conducted in Norway, with a planned inclusion of 40 patients.
The objective of the PROSARC-2 trial is to investigate whether dose-escalated hypofractionated, definitive, proton beam therapy (PBT) can result in better local control in soft tissue sarcoma (STS). PROSARC-2 is a single arm, open-label, multicenter phase II clinical trial initiated at the Department of Oncology, Oslo University Hospital (OUS). The main inclusion criterion is patients with inoperable soft tissue sarcoma. The primary endpoint is 2-year local progression-free survival (LPFS). We expect to include 40 patients over three years and all patients will be followed for up to five years. All the sarcoma centers in Norway participate in the study: OUS; Haukeland University Hospital (HUH); St Olavs Hospital (SOH) and University Hospital of North-Norway (UNN). The indication for definitive radiotherapy (RT) will be decided in the sarcoma multidisciplinary (MDT) meeting at each center. A weekly/biweekly national sarcoma RT meeting will make the decision whether hypofractionated, dose-escalated PBT will be feasible after a careful clinical evaluation. For included patients PBT will be given at OUS and HUH. The prescribed dose is 56 Gray (Gy) in 16 fractions over 4 weeks (14 Gy per week) with a maximum dose-escalation to the tumor core of 80 Gy (5 Gy per fraction).
The PROSARC-2 trial includes translational radiomic research, where we aim to elucidate underlying mechanisms related to RT effect. To facilitate future biomarker studies for personalized therapy we will collect excess tumor tissue, whole blood, plasma and serum.
1,607 studies on the registry are indexed under Sarcoma; 366 are open to participants now.
This study's planned enrollment of 40 is close to the median of 40 across 1,255 interventional studies indexed under Sarcoma.
Browse Sarcoma studies →Oslo University Hospital is the lead sponsor of 834 studies on the registry; 149 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
The amount of disease can be tracked with a defined measurement, so the study can see whether it shrinks or grows. It might be a tumour measured on a scan or, in some blood cancers such as myeloma, a marker measured in blood or urine.
The criteria or the study team say which measurement counts — having no tumour visible on a scan does not by itself rule you out.
The standard rules for measuring tumours on CT or MRI scans, to tell whether a cancer is shrinking, stable or growing during treatment.
“Measurable disease per RECIST 1.1” usually means at least one tumour 10 mm or more at its longest on a CT scan, or a lymph node 15 mm or more across its short axis.
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Measurable disease
The amount of disease can be tracked with a defined measurement, so the study can see whether it shrinks or grows. It might be a tumour measured on a scan or, in some blood cancers such as myeloma, a marker measured in blood or urine.
The criteria or the study team say which measurement counts — having no tumour visible on a scan does not by itself rule you out.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
RECIST
The standard rules for measuring tumours on CT or MRI scans, to tell whether a cancer is shrinking, stable or growing during treatment.
“Measurable disease per RECIST 1.1” usually means at least one tumour 10 mm or more at its longest on a CT scan, or a lymph node 15 mm or more across its short axis.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECOG performance status
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Metastases
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Radiation: Definitive radiotherapy
The prescribed dose is 56 Gray (Gy) in 16 fractions over 4 weeks (14 Gy per week) with a maximum dose-escalation to the tumor core of 80 Gy (5 Gy per fraction).
Local progression-free survival
Local progression-free survival is measured from the date of start of study treatment until date of local progression of the tumor that has undergone proton beam radiotherapy evaluated using RECIST v1.1 or date of death of any cause, whichever occurs first.
Time frame: 2 Year
Progression-free survival
Progression-free survival is measured from the date of start of study treatment until date of progressive disease (local and/or distant) as evaluated using RECIST v1.1 or date of death of any cause, whichever occurs first.
Time frame: Up to five years after radiation therapy
Overall survival
Overall survival is measured from the date of start of study treatment until date of death of any cause.
Time frame: Up to five years after radiation therapy.
Overall response rate, defined as partial or complete response using RECIST v1.1
Radiological response will be assessed using MRI and/or CT of the primary tumor.
Time frame: Up to five years after radiation therapy.
Health-related quality of life
Change from baseline in EORTC QLQ-C30 scores.
Time frame: Up to five years after radiation therapy.
To assess acute and late toxicity
Treatment-related toxicity during treatment and follow-up using CTCAE v5.0.
Time frame: Up to five years after radiation therapy.
Plan to share: Yes
Supporting information: Study protocol, Statistical analysis plan, Informed consent form, Clinical study report
No publications or documents are linked to this record.
Started Jan 2026 (actual). Primary completion is estimated for Jan 2029, 36 months after the start.
Of 198 non-industry phase 2 interventional studies under Sarcoma, half reached primary completion within 66 months of starting (the median), counting those still running; a quarter within 46 and three quarters within 91. This study's planned 36 months is below that.
Counting every sponsor, half of 227 studies reached it within 66 months; a quarter within 43 and three quarters within 92.
How these figures are worked out, and which studies are left out of them.
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