NCT07292298

Phase 2 Single-Arm Rectal Cancer Brachytherapy for Patients With Low-Lying Residual Adenocarcinoma After Total Neoadjuvant Therapy to Improve Organ Preservation Rates

• Status: Recruiting
• Phase: Phase 2
• Study type: Interventional
• Enrollment: 44 (estimated)
• Sponsor: University of Colorado, Denver · Academic / Other
• Sex: All
• Age: 18 Years – 100 Years
• Healthy volunteers: Not accepted

Summary

Rectal cancer patients who do not achieve a complete response to standard of care chemotherapy and radiation often require surgical resection as part of curative intent therapy. This study will evaluate whether additional "focal" radiation delivered internally (rectal brachytherapy) can provide complete responses and thus spare the requirement for surgery. The main questions are whether: 1) rectal brachytherapy is safe in this clinical treatment paradigm and if 2) rectal brachytherapy improves organ preservation (no need for surgery). The trial involves an additional MRI pelvis and sigmoidoscopy with marker placement to define high-risk residual disease for radiation planning. Subsequently, 3 outpatient brachytherapy treatments are given on a weekly basis. If a patient achieves a complete response to brachytherapy, standard of care non-operative surveillance visits are conducted with study visits aligned during the first two years following brachytherapy.

Detailed description

Rectal cancer patients with incomplete responses following standard of care chemotherapy and radiation are offered surgery as part of curative intent regimens. Similarly, patients with near-complete responses following initial therapy may require future salvage surgery given high local recurrence risk in the rectum. The goal of this study is to determine whether additional "internal" focal radiation delivered by rectal brachytherapy can provide a complete tumor response, such that patients can avoid surgical intervention. While rectal brachytherapy efficacy, technique, and safety has been demonstrated in previous studies conducted in Europe and Canada, it has not been tested to "boost" responses following standard of care chemotherapy/radiation in the United States. Specifically, rectal brachytherapy treatment requires placement of a multichannel cylinder into the rectum following local analgesia and oral medication to improve procedure tolerability. A balloon on the cylinder is inflated to displace rectum uninvolved with tumor away from the internal high-dose radiation source that travels through the cylinder channels abutting the tumor. 21 Gy cumulative dose over 3 weekly treatments is administered to the high-risk rectal mucosa at a depth aligning to tumor thickness. The cylinder will be immobilized in the rectum for up to 3 hours during each of the 3 brachytherapy sessions, with radiation treatment being less than 10 minutes following completion of planning. If complete response is achieved, surveillance visits will be conducted with an almost identical protocol to patients who achieve complete response following standard of care radiation/chemotherapy.

Conditions

• Rectal Adenocarcinoma
• Rectal Cancer

Interventions

Type	Name	Description
RADIATION	High Rare Dose Rectal Brachytherapy Boost	HDR rectal brachytherapy boost using Iridium-192 delivered via an intracavitary applicator in three weekly fractions (total dose: 21 Gy) for patients with low-lying residual rectal adenocarcinoma following total neoadjuvant therapy.

Timeline

• Start date: 2026-11-01
• Primary completion: 2030-11-01
• Completion: 2031-11-01
• First posted: 2025-12-18
• Last updated: 2026-04-06

Locations

3 sites across 1 country: United States