Preventive Efficacy of Bergmann Enema for Acute Radiation-induced Rectal Injury in Rectal Cancer Patients Undergoing Short-course Radiotherapy

Research Objective and Principle: To evaluate the effectiveness of Bergmann enema in preventing acute radiation-induced rectal injury in patients with rectal cancer, thereby providing a basis for treatment options for potential radiation-induced rectal injury patients, aiming for adoption by international guidelines. Primary Objective: Incidence of grade 2 or higher radiation-induced rectal injury. Secondary Objectives: Severity of radiation-induced rectal injury, completion rate of short-course radiotherapy, safety of Bergmann enema, quality of life, pathological complete response (pCR) rate. Study Design: Prospective, single-center, single-arm study. Study Population and Expected Enrollment: Patients with rectal cancer undergoing short-course radiotherapy, expecting to enroll 40 patients. Trial Duration: From December 2025 to December 2026. Intervention: Patients will receive Bergmann enema (30 ml) once daily from the start of radiotherapy until the 10th day after the end of radiotherapy. Statistical Hypothesis: Based on previous reports, the incidence of acute radiation-induced rectal injury is 80%, and it is expected that Bergmann enema preventive treatment can reduce it to 50%. The sample size was estimated using a formula designed to calculate single-group rate, with a set at 0.05 and a power of 80%. The study aimed to enroll at least 36 patients. Considering a dropout rate of 10%, at least 40 patients need to be included.