Adding Spatially Fractionated Radiation Therapy to Standard Palliative Radiation for Improving Disease-Related Symptoms in Patients With Unresectable Solid Tumors

October 22, 2026 updated by: Mayo Clinic

Multicenter, Randomized Phase II Trial on Palliative Radiation With or Without Spatially Fractionated Radiotherapy Boost for Unresectable Bulky Malignancies

This clinical trial evaluates whether adding spatially fractionated radiation therapy (SFRT) to standard palliative external beam radiation therapy (EBRT) improves disease-related symptoms in patients with solid tumors that cannot be removed by surgery (unresectable). SFRT, originally termed GRID therapy, is a radiation therapy technique designed to deliver a highly uneven dose of radiation to a tumor. This is achieved by using a grid-like pattern, where isolated regions receive high doses, while the spaces between experience significantly lower doses. This method allows for a greater total dose to be delivered to the tumor while potentially reducing damage to surrounding healthy tissues. EBRT is a type of radiation therapy that uses a machine to aim high-energy rays at the cancer from outside of the body. Adding SFRT to standard palliative EBRT may improve disease-related symptoms such as pain, difficulty breathing, bleeding, or difficulty swallowing in patients with unresectable solid tumors.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
100

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • United States
    • Arizona
      • Scottsdale, Arizona, United States, 85259
        • Recruiting
        • Mayo Clinic in Arizona
        • Contact:
        • Principal Investigator:
          • Diego A. Santos Toesca, MD
    • Minnesota
      • Rochester, Minnesota, United States, 55905
        • Recruiting
        • Mayo Clinic in Rochester
        • Contact:
        • Principal Investigator:
          • Meng X. Welliver, MD, PhD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

15 years and older (Child, Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Histologically proven primary or metastatic solid malignant tumors from any histologic subtype
  • Measurable primary or metastatic bulky tumor defined as tumor > 5 cm in largest dimension not eligible for surgical resection or not an ideal candidate for alternative local therapies, e.g., cryoablation, etc.
  • Eastern Cooperative Oncology Group (ECOG) performance status 0-3 assessed within 30 days of enrollment
  • Estimated life expectancy > 3 months, as judged by treating clinician
  • Patients must sign Institutional Review Board (IRB) approved study specific informed consent
  • Patients must complete all required pre-entry tests within the specified time limits
  • Patients must be able to start treatment (radiation) within 60 days of study registration
  • Patients must be at least 15 years old
  • A minimum most prominent symptom intensity score reported by the patient of >= 5 on an 11-point symptom intensity scale (item 4.3.2), clearly related to the target lesion, within one the following: pain, dyspnea, hemorrhage, or dysphagia

Exclusion Criteria:

  • Prior RT to the current target site < 3 months from randomization

  • Intracranial invasion by the proposed tumor target or tumor target intertwined with bowel loops

  • Concurrent systemic therapy (e.g., chemotherapy, immunotherapy) during RT delivery will not be an exclusion condition

  • Active rectal diverticulitis, Crohn's disease affecting the rectum, or ulcerative colitis (non-active diverticulitis and Crohn's disease not affecting the rectum are allowed), for patients whose target tumor is in the pelvis

  • Major medical, addictive, or psychiatric illness which in the investigator's opinion, will prevent the consent process, completion of the treatment and/or interfere with follow-up. Consent by legal authorized representative is not permitted for this study

  • History of myocardial infarction or decompensated congestive heart failure (CHF) within the last 6 months

  • On a transplant list

  • Any of the following are excluded because this study involves ionizing radiation:

    • Pregnant persons
    • Nursing persons
    • Persons of childbearing potential who are unwilling to employ adequate birth control measures will be asked to stay on adequate forms of birth control until study intervention (therapy) is finished

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Group I (SFRT, EBRT)

Patients undergo a single fraction of SFRT. Starting 1-3 days after SFRT, patients undergo standard palliative EBRT in a dose regimen determined by the treating physician.
Other: Questionnaire Administration

Ancillary studies

Other: Electronic Health Record Review

Ancillary studies

Radiation: External Beam Radiation Therapy

Undergo standard palliative EBRT

Other Names:
  • EBRT
  • Definitive Radiation Therapy
  • External Beam Radiation
  • External Beam Radiotherapy
  • External Beam RT
  • external radiation
  • External Radiation Therapy
  • external-beam radiation
  • Radiation, External Beam
  • Teleradiotherapy
  • Teletherapy
  • Teletherapy Radiation
  • External Beam Radiotherapy (conventional)
Radiation: Spatially-fractionated Radiation Therapy

Undergo SFRT

Other Names:
  • SFRT
  • GRID Therapy
  • Spatially Fractionated Radiation Therapy
Active Comparator: Group II (EBRT)

Patients undergo standard palliative EBRT in a dose regimen determined by the treating physician.
Other: Questionnaire Administration

Ancillary studies

Other: Electronic Health Record Review

Ancillary studies

Radiation: External Beam Radiation Therapy

Undergo standard palliative EBRT

Other Names:
  • EBRT
  • Definitive Radiation Therapy
  • External Beam Radiation
  • External Beam Radiotherapy
  • External Beam RT
  • external radiation
  • External Radiation Therapy
  • external-beam radiation
  • Radiation, External Beam
  • Teleradiotherapy
  • Teletherapy
  • Teletherapy Radiation
  • External Beam Radiotherapy (conventional)

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Response at 1 month - Patient-reported Impression of Change
Time Frame: Baseline to 1 month follow-up

Participants rate the most prominent symptom related to the target lesion to be treated on a 7-point scale ranging from -3 (very much worse) to +3 (very much better). Response will be reported as a binary yes/no, defined as a patient reporting that the symptom is moderately better or very much better 1 month after completing treatment.
Baseline to 1 month follow-up

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Change in Patient-reported Most Prominent Symptom Intensity
Time Frame: Baseline to 1 month follow-up

Participants will record the severity of the most prominent symptom related to the target lesion (e.g., pain, dyspnea, hemorrhage, dysphagia) using an 11-point Likert scale ranging from 0 (none) to 10 (unbearable). A between-group comparison of the magnitude of the severity scores will be made.
Baseline to 1 month follow-up
Response at 3 months - Patient-reported Impression of Change
Time Frame: At 3 month follow-up

Participants rate the most prominent symptom related to the target lesion to be treated on a 7-point scale ranging from -3 (very much worse) to +3 (very much better). Response will be reported as a binary yes/no, defined as a patient reporting that the symptom is moderately better or very much better 3 months after completing treatment.
At 3 month follow-up
Radiographic tumor response
Time Frame: At 3 month follow-up

Radiographic tumor response at 3 months post-treatment will be assessed by a modified Response Evaluation Criteria in Solid Tumors (RECIST) criteria. Radiographic tumor response will be coded as a 1 if the patient meets the complete response (CR) or partial response (PR) modified RECIST criteria and 0 otherwise. Per the modified RECIST criteria, CR will be defined as disappearance of the target lesion, PR will be defined as ≥30% decrease in longest diameter (LD) of target lesion as compared to baseline measurement, Progressive Disease (PD) will be defined as ≥20% increase in LD of target lesion as compared to baseline measurement, and Stable Disease (SD) will be defined as not meeting the criteria for CR, PR, or PD.
At 3 month follow-up

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Mayo Clinic

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Diego Augusto Santos Toesca, MD, Mayo Clinic

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
September 23, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
September 30, 2031

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
September 30, 2031

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
September 23, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
September 23, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
October 2, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
October 26, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
October 22, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
October 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • GMROA2481
  • NCI-2026-06455 (Registry Identifier: CTRP (Clinical Trial Reporting Program))
  • 25-005298 (Other Identifier: Mayo Clinic Institutional Review Board)

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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