This prospective observational study will enroll 50 adults who are scheduled to receive radiotherapy to the abdomen or pelvis. The study will not assign any additional treatment or change routine clinical care. Residual blood samples from routine clinical testing will be collected before radiotherapy, at the end of radiotherapy, and one month after radiotherapy to measure plasma glucagon-like peptide-2 (GLP-2).
Participants will be followed for gastrointestinal symptoms and the occurrence and severity of acute radiation enteritis. Researchers will compare GLP-2 levels and changes between participants who develop acute radiation enteritis and those who do not. The study will also examine the associations of GLP-2 with markers of intestinal barrier injury and inflammation, radiotherapy dose parameters, nutritional status, and quality of life. The aim is to explore whether plasma GLP-2 may help assess the risk and severity of acute radiation enteritis.