This is a prospective, observational study aimed at exploring the associations between the clinical subtypes of radiation rectal injury and prognosis. The study is planed to commence in November 2025 and prospectively observe 150 patients. During the study period, researchers will not intervene in clinical treatment decisions but will only collect patient clinical information, intestinal endoscopy/imaging/pathological data, test results, and follow-up data. The study results will fill the evidence gap in this field, advance the diagnosis and treatment of radiation-induced rectal injury, and provide scientific support for improving the prognosis of similar patients.