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

University Hospital Tuebingen

Status and phase

Not yet enrolling

Phase 2

Conditions

Rectal Cancer

Treatments

Radiation: Dose escalated radiotherapy using a 1.5 T MR-Linac

Study type

Interventional

Funder types

Other

Identifiers

NCT07337876

311/2025BO1

Details and patient eligibility

About

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.

Enrollment

100 estimated patients

Sex

All

Ages

18+ years old

Volunteers

No Healthy Volunteers

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).