Functional Recovery After Chemotherapy- and Radiotherapy-Induced Gastrointestinal Injury: Mechanisms, Clinical Assessment, and Management

Abstract: Chemotherapy- and radiotherapy-induced gastrointestinal injury is a common complication of cancer treatment and may present with diarrhea, abdominal pain, urgency, bloating, rectal bleeding, and reduced oral intake. Although many cases improve after treatment completion, some patients develop persistent or late bowel dysfunction that impairs nutrition, treatment tolerance, daily functioning, and quality of life. Conventional terms such as toxicity, mucositis, and enteritis are clinically useful, but they do not fully capture the problem of incomplete functional recovery. We propose a practical recovery-oriented framework that operationalizes meaningful recovery across four interconnected domains: structural recovery, barrier recovery, clinical recovery, and patient-centered recovery. Using this framework, we summarize the acute-to-chronic clinical spectrum of luminal gastrointestinal injury, examine mechanisms of failed recovery, review clinical assessment and management, and discuss emerging strategies including biomarker-guided monitoring, microbiome-directed interventions, organoid-based platforms, and regenerative therapies. Current care remains largely supportive and symptom-centered. A recovery-oriented model may improve clinical decision-making by integrating symptom trajectory, nutritional status, treatment tolerance, patient-reported burden, and selected biological signals to better monitor and restore gastrointestinal function. Keywords: chemotherapy, radiotherapy, gastrointestinal injury, functional recovery, clinical assessment, survivorship