A Prospective, Single-Arm Clinical Study of a Dietary Supplement for the Prevention of Acute Radiation-Induced Rectal Injury During Neoadjuvant Chemoradiotherapy for Rectal Cancer

This clinical study is a prospective, single-arm, single-center trial aimed at assessing the safety and efficacy of tributyrin (TB) as a dietary supplement for preventing acute radiation-induced rectal injury (ARII). Approximately 23 participants with locally advanced rectal cancer will receive tributyrin in addition to standard neoadjuvant chemoradiotherapy. We hypothesize that tributyrin will reduce the incidence of grade 2 or higher ARII, graded according to the RTOG/EORTC criteria. Treatment-related adverse events will be assessed using the Common Terminology Criteria for Adverse Events (CTCAE), and changes in health-related quality of life and bowel function will be assessed using the EORTC QLQ-C30 and IBD-Q questionnaires.

Inclusion Criteria: 1. Histologically confirmed rectal adenocarcinoma. 2. Clinically staged as locally advanced rectal cancer (cT3-4 and/or N+). Planned to receive short-course radiotherapy or long-course radiotherapy combined with concurrent fluoropyrimidine-based chemotherapy. 3. ECOG performance status of 0 or 1. 4. Baseline defecation frequency \< 3 times/day, with no significant abdominal pain or tenesmus. Exclusion Criteria: 1. Previous history of total mesorectal excision (TME) or other intestinal resection surgeries. 2. Diagnosis of severe diarrhea, Crohn's disease, ulcerative colitis, or chronic radiation enteritis. 3. Previous history of pelvic radiotherapy. 4. Presence of malignant pleural effusion or malignant ascites, or complete/incomplete intestinal obstruction, rendering the patient unable to tolerate dietary supplement therapy. 5. Participation in other investigational drug trials within 4 weeks prior to enrollment. 6. Receiving non-conventional chemotherapy regimens (non-fluoropyrimidine drugs) or concurrent participation in other trials involving potent mucosa-damaging drugs. 7. Pregnant or breastfeeding women. 8. History of alcoholism, drug abuse, or substance abuse within the past 1 year. 9. History of severe allergies or known allergy to the ingredients of the dietary supplement.