HDR Endorectal Brachytherapy With 3D-Printed Guidance and Local Shielding for Rectal Cancer Organ Preservation

NCT07786493 | Not Yet Recruiting

• 1 other identifier: E20260970
• Study Type: interventional
• Target: 50
• Locations: 1 country
• Sites: 1

Brief Summary

This prospective, single-center, single-arm phase II study will evaluate the efficacy, safety, and technical feasibility of an organ-preserving radiotherapy strategy for patients with localized rectal adenocarcinoma who are medically inoperable, decline radical surgery, or are considered technically unresectable without distant metastases. Participants will receive pelvic external beam radiotherapy followed by high-dose-rate (HDR) endorectal brachytherapy. Concurrent capecitabine may be given during external beam radiotherapy to participants who are considered able to tolerate chemotherapy. During HDR brachytherapy, all participants will be treated using a patient-specific 3D-printed guide template and individualized tungsten-alloy local shielding. The guide template is designed to improve applicator positioning and treatment reproducibility, while the local shielding is intended to reduce radiation exposure to non-target rectal wall. The study will enroll 50 participants. The primary objectives are to evaluate the 12-month clinical complete response rate and the technical completion rate of the HDR brachytherapy platform. Secondary assessments include organ preservation, local regrowth, survival outcomes, treatment-related toxicity, quality of life, and anorectal function.

Conditions

Rectal Cancer, Adenocarcinoma

Keywords

Rectal cancer; Organ preservation; High-dose-rate brachytherapy; Endorectal brachytherapy; 3D-printed template; Tungsten alloy shielding

Outcome Measures

Primary Outcomes (2)

• 12-Month Clinical Complete Response Rate

  Percentage of participants who maintain a clinical complete response (cCR) at 12 months after completion of study treatment, without local regrowth and without rectal cancer-related salvage resection. Clinical response will be assessed using a composite evaluation including digital rectal examination, endoscopy, and pelvic magnetic resonance imaging.

  From completion of study treatment through 12 months

• Technical Completion Rate of HDR Brachytherapy

  Percentage of participants who complete all three planned high-dose-rate (HDR) endorectal brachytherapy fractions using the study-specific 3D-printed individualized guide template and tungsten alloy local shielding platform as required by the study protocol.

  Through completion of HDR brachytherapy, approximately 8-10 weeks after completion of external beam radiotherapy

Secondary Outcomes (10)

• Overall Clinical Complete Response Rate

  From completion of study treatment through 12 months

• Near-Clinical Complete Response Rate

  From completion of study treatment through 12 months

• 12-Month Organ Preservation Rate

  From completion of study treatment through 12 months

• Local Regrowth Rate

  From completion of study treatment through 24 months

• Local Failure-Free Survival

  from enrollment through 24 months

Study Arms (1)

HDR Brachytherapy-Based Organ Preservation

EXPERIMENTAL

Participants will receive definitive organ-preserving treatment for rectal cancer, including external beam radiotherapy with concurrent chemotherapy as clinically indicated, followed by high-dose-rate brachytherapy for local dose intensification. Patient-specific treatment planning and study-specific brachytherapy techniques will be performed according to the study protocol.

Radiation: High-Dose-Rate Endorectal Brachytherapy

Interventions

High-Dose-Rate Endorectal Brachytherapy RADIATION

High-dose-rate (HDR) endorectal brachytherapy will be delivered as a local dose-intensification component of the organ-preserving treatment strategy for rectal cancer. Brachytherapy will be performed using image-guided, patient-specific treatment planning to optimize target coverage while limiting radiation exposure to adjacent organs at risk. Treatment technique, applicator placement, dose prescription, and fractionation will be performed according to the study protocol.

HDR Brachytherapy-Based Organ Preservation

Eligibility Criteria

• Age: 18 Years - 80 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Age 18-80 years.
• Histologically confirmed rectal adenocarcinoma.
• Clinical stage cT2-4, any N, M0.
• Patients who are elderly or frail, medically unsuitable for radical surgery, refuse radical surgery, or are considered by a multidisciplinary team (MDT) to have disease for which safe R0 resection is technically difficult.
• Considered by the MDT and investigators to be suitable for a definitive non-operative treatment strategy.
• ECOG performance status 0-2; patients with ECOG performance status 3 may be eligible if considered by the MDT to be able to tolerate the study treatment.
• Estimated life expectancy of at least 6 months.
• Considered suitable for pelvic external beam radiotherapy and HDR endorectal brachytherapy.
• Tumor location, endorectal access, and local anatomy suitable for HDR brachytherapy using the individualized 3D-printed guide template.
• Adequate hematologic, hepatic, and renal function for the planned treatment.
• Ability to understand the study requirements and provide written informed consent.

You may not qualify if:

• Distant metastatic disease or disease considered unsuitable for definitive local non-operative treatment.
• Prior definitive pelvic radiotherapy.
• Intestinal perforation, complete bowel obstruction, uncontrolled active bleeding, or severe active infection.
• Anatomical or clinical conditions precluding HDR endorectal brachytherapy or use of the individualized guide template/local shielding platform.
• Inflammatory bowel disease.
• Severe uncontrolled cardiopulmonary disease, significant bone marrow suppression, or severe hepatic or renal dysfunction.
• Pregnancy or breastfeeding.
• Concurrent participation in another clinical trial that may interfere with evaluation of the study treatment or endpoints.
• Any other condition considered by the investigator to make the patient unsuitable for participation in the study.

Sponsors & Collaborators

• Tianjin Medical University Cancer Institute and Hospital: lead

Study Sites (1)

Tianjin Medical University Cancer Institute and Hospital

Tianjin, Tianjin Municipality, 300060, China

Location

Related Publications (1)

• Cao Y, Li C, Zhang B, Chen J. HDR Endorectal/Endoluminal Brachytherapy Boost in Rectal Organ Preservation: A Systematic Review and Meta-Analysis. Cancers (Basel). 2026 May 6;18(9):1494. doi: 10.3390/cancers18091494.

  PMID: 42122288 BACKGROUND

MeSH Terms

Conditions

Rectal Neoplasms

Condition Hierarchy (Ancestors)

Colorectal Neoplasms; Intestinal Neoplasms; Gastrointestinal Neoplasms; Digestive System Neoplasms; Neoplasms by Site; Neoplasms; Digestive System Diseases; Gastrointestinal Diseases; Intestinal Diseases; Rectal Diseases

Study Officials

• Yuanjie Cao, MD

  Tianjin Medical University Cancer Institute and Hospital

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Yuanjie Cao, MD

CONTACT

86-18522123151; cyjro325@tjmuch.com

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: August 20, 2026
• First Posted: August 26, 2026
• Study Start (Estimated): September 1, 2026
• Primary Completion (Estimated): November 30, 2029
• Study Completion (Estimated): November 30, 2030
• Last Updated: August 26, 2026

Record last verified: 2026-08

Data Sharing

• IPD Sharing: Will not share

Locations

CN (1)