Abdominal TumorACTIONNCT07687147
Daily Adjustment of the Radiation Dose in MRI-guided Stereotactic Radiotherapy for Tumors in the Abdominal and Pelvic Regions
A study testing SBRT with adaptive fractionation in people with Abdominal Tumor and Pelvic Tumor, run by University of Zurich at 1 site in Switzerland.
Trial summary
SBRT delivers high-dose radiation to precisely defined target volumes and is an effective locally ablative treatment option for both primary tumours and oligometastases in various settings, including lesions in the abdomen or pelvis. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Abdominal Tumor, Pelvic Tumor
- What is being tested?
- SBRT with adaptive fractionation
- Type of treatment
- Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 100 participants
- Where
- 1 siteSwitzerland
- Study dates
- 16 Jun 2026to Dec 2028
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Karnofsky performance status ≥70
- Abdominal or pelvic malignancy (primary or secondary) with previous histological confirmation of the primary tumour, amenable to SBRT in 5 fractions (excluding SBRT to primary tumour in patients with prostate cancer) Note: patients with primary prostate cancer are eligible, but SBRT to the primary tumour in the prostate cannot be performed within the study
- Total prescribed SBRT dose > 30 Gy (constraint for dose-limiting OAR) over 5 treatment fractions
- Distance of the GTV ≤ 1 cm from at least one dose-limiting OAR (bowel / duodenum / stomach) in the available diagnostic images
- Patients able to tolerate long (approximately 60 minutes) treatment time according to clinical evaluation of the treating radiation oncologist
- Patients willing and able to comply with scheduled visits, treatment, and other trial procedures
Who cannot join
- Previous radiation therapy directly overlapping with planned SBRT (type I re-irradiation)
- More than one PTV irradiated in the same plan
- Contraindications for MRI, e.g., patients with metal fragments or implanted devices that are not MR compatible such as certain types of pacemakers and aneurysm clips or severe claustrophobia
- SBRT not indicated or not possible
- Inability to follow the procedures of the trial, e.g. due to language problems of the participant
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Lena Kretzschmar, Dr. med. contact
Switzerland1 site, 1 recruiting
- Recruiting
University Hospital Zurich
Zurich, Canton of Zurich, 8091
About this study
Official title: Adaptive Fractionation in Online MR-guided SBRT for Abdominal and Pelvic Target Volumes
SBRT delivers high-dose radiation to precisely defined target volumes and is an effective locally ablative treatment option for both primary tumours and oligometastases in various settings, including lesions in the abdomen or pelvis. However, SBRT in these regions faces considerable challenges such as inter-fractional organ motion and anatomical deformation, which can compromise treatment precision.
MR-guided SBRT offers a solution, providing superior soft-tissue contrast and enabling real-time, online treatment plan adaptation over the course of SBRT. This approach reduces the risk of geographical miss and overdose to adjacent, vulnerable OARs. Currently, MR-guided SBRT uses a fixed dose per fraction, only adjusting target volume and OAR contours for anatomical changes when performing plan adaptation. However, overlaps between planning target volumes (PTVs) and dose-limiting OARs regularly require compromises in PTV coverage. To address this, AF aims to also adjust dose per fraction based on daily PTV-OAR overlap. With this approach, more dose is applied on treatment days with less PTV-OAR overlap while less dose is applied on days with more PTV-OAR overlap. This trial assesses the feasibility of AF in MR-guided SBRT for abdominal and pelvic tumours that show PTV-overlap with one or more dose-limiting OARs, ultimately aiming to enhance PTV dose coverage without increasing toxicity.
- Conditions
- Abdominal Tumor, Pelvic Tumor
- Being tested
- SBRT with adaptive fractionation, Standard of Care (SOC)
- Keywords
- adaptive radiotherapy, stereotactic body radiotherapy, SBRT, MR-guided radiotherapy
- Medical subject headings
- Abdominal Neoplasms, Pelvic Neoplasms
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
SBRT with adaptive fractionationRadiation
The fraction dose to the PTV will be adapted based on the volume overlap of PTV and the dose-limiting OAR(s) (bowel / duodenum / stomach) on the planning MRI scan of the day ("geometry-of-the-day"). The treatment plan is then approved by the treating physician and independently verified according to department-internal standard. MR-guided fraction dose adaptation will be repeated at each of the 5 fractions, until the prescribed total dose is reached.
Standard of Care (SOC)Radiation
Patients that qualify for inclusion in the study but for whom AF is no viable treatment due to lacking PTV/OAR overlap in the planning scans. These patients are treated according to clinical standard of care (SoC), i.e. without dose adaptation, and function as a control group.
| Study group | Role | What they receive |
|---|---|---|
| RT with AF | Experimental | Patients with PTV/OAR overlap will receive AF, with dose adapted daily based on anatomy. Receives: Radiation: SBRT with adaptive fractionation |
| RT without AF | Active comparator | Patients without PTV/OAR overlap will receive standard fractionated treatment. Receives: Radiation: Standard of Care (SOC) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Proportion of patients with successful daily dose adaptation
Proportion of patients treated with daily dose-adapted treatment, who received at least one fraction of non-uniformly fractionated treatment with expectation of a benefit in PTV-coverage of ≥ 1ccGy
Measured: from enrollment to end of treatment at 1-2 weeks
Secondary outcomes (4)
Acute treatment toxicities
Acute treatment toxicities for all included patients measured with Common Terminology Criteria for Adverse Events
Measured: during treatment (1-2 weeks) and until 90 days after
Interfractional variation in PTV/OAR overlap volume
interfractional variation in PTV/OAR overlap volume, in cc
Measured: during treatment (1-2 weeks)
Interfractional variation in GTV/OAR distance
interfractional variation in GTV/OAR distance, in mm
Measured: during treatment (1-2 weeks)
Dosimetric difference in PTV-coverage between algorithm-based calculation and the reference plan
PTV coverage quantified as the area above the dose-volume-histogram curve measured in cc x Gy
Measured: after end of treatment (2 weeks after last fraction)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted7 Jul 2026
- Study start16 Jun 2026
- Primary completionDec 2028 (estimated)
- Study completionDec 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Abdominal TumorStudies of the same condition, open and under way.
- More trials run by University of ZurichThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 100 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Zurich
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Reinhardt Krcek, Dr. med., Principal investigator, University of Zurich
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07687147
- Sponsor's protocol ID
- RAO-25-019
- Other IDs
- 2026-00067
- Acronym
- ACTION
- Status last verified
- Jun 2026
- First submitted
- 30 Apr 2026
- Last updated
- 7 Jul 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 7 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Adaptive Fractionation in Online MR-guided SBRT for Abdominal and Pelvic Target Volumes
- ClinicalTrials.gov ID
- NCT07687147
- Acronym / sponsor ID
- ACTION / RAO-25-019
- Conditions
- Abdominal Tumor, Pelvic Tumor
- Keywords
- adaptive radiotherapy, stereotactic body radiotherapy, SBRT, MR-guided radiotherapy
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 100 participants (estimated)
- Lead sponsor
- University of ZurichUniversity, hospital or other
- Study start
- 16 Jun 2026 (actual)
- Primary completion
- Dec 2028 (estimated)
- Study completion
- Dec 2028 (estimated)
- First posted
- 7 Jul 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
SBRT delivers high-dose radiation to precisely defined target volumes and is an effective locally ablative treatment option for both primary tumours and oligometastases in various settings, including lesions in the abdomen or pelvis. However, SBRT in these regions faces considerable challenges such as inter-fractional organ motion and anatomical deformation, which can compromise treatment precision.
MR-guided SBRT offers a solution, providing superior soft-tissue contrast and enabling real-time, online treatment plan adaptation over the course of SBRT. This approach reduces the risk of geographical miss and overdose to adjacent, vulnerable OARs. Currently, MR-guided SBRT uses a fixed dose per fraction, only adjusting target volume and OAR contours for anatomical changes when performing plan adaptation. However, overlaps between planning target volumes (PTVs) and dose-limiting OARs regularly require compromises in PTV coverage. To address this, AF aims to also adjust dose per fraction based on daily PTV-OAR overlap. With this approach, more dose is applied on treatment days with less PTV-OAR overlap while less dose is applied on days with more PTV-OAR overlap. This trial assesses the feasibility of AF in MR-guided SBRT for abdominal and pelvic tumours that show PTV-overlap with one or more dose-limiting OARs, ultimately aiming to enhance PTV dose coverage without increasing toxicity.
Study design
- Primary purpose
- Treatment
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| RT with AF | Experimental | Radiation: SBRT with adaptive fractionationPatients with PTV/OAR overlap will receive AF, with dose adapted daily based on anatomy. |
| RT without AF | Active comparator | Radiation: Standard of Care (SOC)Patients without PTV/OAR overlap will receive standard fractionated treatment. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (6 listed)
- Karnofsky performance status ≥70
- Abdominal or pelvic malignancy (primary or secondary) with previous histological confirmation of the primary tumour, amenable to SBRT in 5 fractions (excluding SBRT to primary tumour in patients with prostate cancer) Note: patients with primary prostate cancer are eligible, but SBRT to the primary tumour in the prostate cannot be performed within the study
- Total prescribed SBRT dose > 30 Gy (constraint for dose-limiting OAR) over 5 treatment fractions
- Distance of the GTV ≤ 1 cm from at least one dose-limiting OAR (bowel / duodenum / stomach) in the available diagnostic images
- Patients able to tolerate long (approximately 60 minutes) treatment time according to clinical evaluation of the treating radiation oncologist
Key exclusion criteria (5 listed)
- Previous radiation therapy directly overlapping with planned SBRT (type I re-irradiation)
- More than one PTV irradiated in the same plan
- Contraindications for MRI, e.g., patients with metal fragments or implanted devices that are not MR compatible such as certain types of pacemakers and aneurysm clips or severe claustrophobia
- SBRT not indicated or not possible
- Inability to follow the procedures of the trial, e.g. due to language problems of the participant
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| SBRT with adaptive fractionationThe fraction dose to the PTV will be adapted based on the volume overlap of PTV and the dose-limiting OAR(s) (bowel / duodenum / stomach) on the planning MRI scan of the day ("geometry-of-the-day"). The treatment plan is then approved by the treating physician and independently verified according to department-internal standard. MR-guided fraction dose adaptation will be repeated at each of the 5 fractions, until the prescribed total dose is reached. | Radiation | RT with AF |
| Standard of Care (SOC)Patients that qualify for inclusion in the study but for whom AF is no viable treatment due to lacking PTV/OAR overlap in the planning scans. These patients are treated according to clinical standard of care (SoC), i.e. without dose adaptation, and function as a control group. | Radiation | RT without AF |
Primary outcome
Proportion of patients with successful daily dose adaptation
Time frame: from enrollment to end of treatment at 1-2 weeks
Proportion of patients treated with daily dose-adapted treatment, who received at least one fraction of non-uniformly fractionated treatment with expectation of a benefit in PTV-coverage of ≥ 1ccGy
4 secondary outcomes
Acute treatment toxicities
Time frame: during treatment (1-2 weeks) and until 90 days after
Interfractional variation in PTV/OAR overlap volume
Time frame: during treatment (1-2 weeks)
Interfractional variation in GTV/OAR distance
Time frame: during treatment (1-2 weeks)
Dosimetric difference in PTV-coverage between algorithm-based calculation and the reference plan
Time frame: after end of treatment (2 weeks after last fraction)
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 7 Jul 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Lena Kretzschmar, Dr. med. contact
Reinhardt Krcek, Dr. med. principal investigator
University of Zurich
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing SBRT with adaptive fractionation in people with Abdominal Tumor and Pelvic Tumor, run by University of Zurich at 1 site in Switzerland.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 6 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 7 Jul 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Switzerland. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Jan Unkelbach, Prof. Dr. rer. nat. (+41 44 255 85 49, jan.unkelbach@usz.ch), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Proportion of patients with successful daily dose adaptation (time frame: from enrollment to end of treatment at 1-2 weeks). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 7 Jul 2026.