Clinical Research Directory

Inclusion Criteria: Inclusion Criteria: 1. Age 18 to 75 years. 2. Diagnosed with a malignancy and scheduled to receive abdominopelvic radiotherapy. 3. No active enteritis or moderate-to-severe diarrhea before radiotherapy. 4. Expected to complete the planned course of radiotherapy and the 1-month post-radiotherapy follow-up. 5. Able to complete clinical data collection, gastrointestinal symptom assessment, nutritional assessment, quality-of-life assessment, and collection of residual peripheral venous blood samples from routine clinical testing. 6. Willing to participate and able to provide written informed consent. Exclusion Criteria: 1. Moderate-to-severe diarrhea, active inflammatory bowel disease, intestinal obstruction, short bowel syndrome, or severe malabsorption before radiotherapy. 2. Previous radiotherapy to the same abdominopelvic region. 3. Severe cardiac, hepatic, or renal failure. 4. Active infection, severe systemic inflammatory response, or active autoimmune disease. 5. Receipt during the study of treatments considered by the investigator to substantially affect intestinal hormones, inflammatory markers, or intestinal barrier function and interfere with the study results. 6. Pregnancy or breastfeeding. 7. Any other condition that, in the investigator's judgment, makes the individual unsuitable for participation.