Organ Preservation in Rectal Cancer by Dose Escalated MR Guided Adaptive Radiotherapy

Overview

This study is testing whether radiation delivered with MRI guidance using a so-called MR-linac in distal rectal cancer can result in a high rate of organ preservation. Patients will receive radiotherapy together with standard chemotherapy.

Interventions

• Radiation Dose escalated radiotherapy using a 1.5 T MR-Linac
  Dose escalated radiotherapy using a 1.5 T MR-Linac is given to the primary tumor and affected lymph nodes in an online adaptive manner

Primary outcome measures

• Two year TME-free survival [Time frame: Two years from the start of radiotherapy]

Secondary outcome measures (1)

• Clincal complete response rate [Time frame: three months after the end of radiotherapy]

Eligibility criteria

Inclusion criteria

• Patients with histologically confirmed diagnosis of rectal cancer localized between dentate line and 12 cm from the anocutaneous line
• Any MRI staged rectal cancer meeting the following criteria
• cT1-cT3 and
• cN0 -cN1 and
• cM0
• Inclusion of UICC Stage I tumors only if unsuitable for endoscopic resection or if primary surgery would require permanent colostomy or deep anastomosis with expected poor organ function.
• Tumor affects less than 70% of the rectal circumference.
• Maximum longitudinal extension of the tumor less than 8 cm on MRI
• MR-Staging requirements: High-resolution, thin-sliced (i.e.

≤3mm) magnetic resonance imaging (MRI) of the pelvis.

• Cross-sectional imaging of the abdomen and chest to exclude distant metastases.
• Aged at least 18 years. No upper age limit.
• WHO/ECOG Performance Status ≤ 1
• Adequate hematological, hepatic, renal and metabolic function parameters
• Informed consent of the patient

Exclusion criteria

• Lower border of the tumor localised more than 12 cm from the anocutaneous line as measured by rigid rectoscopy
• Distant metastases
• Preexisting fecal incontinence for solid stool
• Prior antineoplastic therapy for rectal cancer
• Prior radiotherapy of the pelvic region
• Subject pregnant or breast feeding, or planning to become pregnant within 6 months after the end of treatment.
• Subject (male or female) is not willing to use highly effective methods of contraception (per institutional standard) during treatment and for 6 months (male or female) after the end of treatment (adequate: oral contraceptives, intrauterine device or barrier method in conjunction with spermicidal jelly).
• Other concomitant antineoplastic therapy
• Serious concurrent diseases, including neurologic or psychiatric disorders (incl. dementia and uncontrolled seizures), active,uncontrolled infections, active, disseminated coagulation disorder
• Other primary tumors with an estimated life expectancy of less than three years
• Contraindications for treatment with 5-Fluorouracil or Capecitabine
• Psychological, familial, sociological or geographical condition potentially hampering compliance with the study protocol and follow-up schedule (these conditions should be discussed with the patient before registration in the trial).

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

N/A

Model

Single group

Masking

Open label

Primary purpose

Treatment

Study locations

Germany · 1 center

• University Hospital Tübingen — Tübingen

Identifiers

NCT: NCT07337876 · 311/2025BO1

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗