Research Objective and Principle: Through a randomized controlled study, evaluate the effectiveness of dexamethasone in improving radiation-induced rectal injury in rectal cancer patients undergoing pelvic radiotherapy, thereby providing evidence for treatment options in patients at risk of radiation-induced rectal injury and aiming for adoption in international guidelines.
Primary Objective: Improvement rate of radiation-induced rectal injury. Secondary Objectives: Severity of radiation-induced rectal injury, completion rate of pelvic radiotherapy, safety of dexamethasone enema, quality of life, pathological complete response (pCR) rate.
Study Design: Prospective, single-center, randomized controlled study. Study Population and Expected Enrollment: Patients with rectal cancer undergoing conventional pelvic radiotherapy, expecting to enroll 40 patients.
Trial Duration: From February 2026 to February 2028.
Intervention:
Experimental Group: Patients will receive enema (dexamethasone 1 mL + normal saline to total 30 mL) once daily from day 10 of radiotherapy until radiotherapy completion.
Control Group: Patients will receive enema (dexamethasone 1 mL + normal saline to total 30 mL) once daily from the occurrence of radiation-induced rectal injury until radiotherapy completion.
Statistical Hypothesis: Based on previous reports, the incidence of acute radiation-induced rectal injury is 86%, and it is expected that the experimental group can reduce it to 40%. The sample size was estimated using a formula designed to compare 2 proportions, 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.
Aged 18 to 75 years, regardless of gender;
Fully understand this study and voluntarily sign the informed consent form, able to comply with the study protocol and complete all trial procedures;
Patients pathologically diagnosed with rectal cancer;
Undergoing conventional pelvic radiotherapy (total dose of 40-50.4Gy in 25-28 fractions);
Severe comorbidities, including uncontrolled stable medical diseases after treatment, or a history of neurological or psychiatric disorders (such as dementia or epilepsy), making them unsuitable for radiotherapy;
Patients who have received pelvic radiotherapy;
Presence of malignant pleural effusion or malignant abdominal effusion, or accompanied by bowel obstruction;
Pregnant or breastfeeding women;