Exploring the Predictive Effect of Intestinal and Oral Microbiota on the Efficacy of Neoadjuvant Radiotherapy and Chemotherapy for Locally Advanced Rectal Cancer Based on Machine Learning

Inclusion Criteria: 1. Voluntary signing of informed consent form 2. Age range: 18-75 years old 3. Diagnosed by histopathological examination and indicated by comprehensive evaluation for neoadjuvant radiotherapy and chemotherapy in locally advanced rectal cancer patients 4. Immunohistochemistry or genetic testing for MSS 5. Imaging shows no distant metastatic lesions 6. ECOG score 0-1 7. All patients are required to complete neoadjuvant concurrent chemoradiotherapy and intraoperative chemotherapy at our center, and return to the hospital on schedule for preoperative evaluation and tumor resection surgery 8. After inspection and evaluation, there is normal bone marrow hematopoiesis, liver and kidney function Exclusion Criteria: 1. Previously received anti-tumor treatment 2. History of other malignant tumors 3. Imaging confirms the presence of distant metastases 4. Patients with MSI-H or dMMR rectal cancer detected by immunohistochemistry or genetic testing 5. Used probiotics, antibiotics, prebiotics, immunosuppressants, and glucocorticoids within the 4 weeks 6. Pathological tissue specimens without assessable efficacy of neoadjuvant therapy 7. Change treatment plan due to disease progression or severe treatment side effects 8. According to the researcher's judgment, it is not suitable to participate in this study