Neoadjuvant Chemoradiation With Nal-IRI and Capecitabine Guided by UGT1A1 Status in Patients With Rectal Cancer

Inclusion Criteria: * Age: 18\~75 years old. * Eastern Cooperative Oncology Group (ECOG) performance status of 0\~1. * Histopathologically confirmed rectal adenocarcinoma. * The lower edge of the primary tumor is located below the peritoneal reflection or located ≤ 10 cm above the anal verge. * Clinical stage: T3-4NanyM0 or T1-2N+M0. * Adequate bone marrow function as evidenced by: Absolute neutrophil count (ANC) ≥1.5×10\^9/L, Platelet count ≥100×10\^9/L, Hemoglobin (Hb) ≥90 g/L. * Adequate hepatic function as evidenced by: Total bilirubin ≤1.5 × upper limit of normal (ULN), Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤2.5×ULN, Serum albumin ≥3 g/dL. * Adequate renal function as evidenced by: Serum creatinine (Cr) ≤1.5 × ULN or creatinine clearance ≥60 mL/min. * Be willing to undergo UGT1A1 gene testing and UGT1A1 genotype of \*1\*1 or \*1\*28. * Accept the neoadjuvant chemoradiotherapy protocol of this study and sign the informed consent. Exclusion Criteria: * Any other malignancy within 5 years, with the exception of cured in-situ carcinoma or basal cell carcinoma etc. * Active, uncontrolled bacterial, viral, or fungal infections that require systemic treatment. * Active HIV infection. * Combined with uncontrollable systemic diseases. * History of allergy or hypersensitivity to drug or any of their excipients. * Any clinical indicators indicating contraindications to radiotherapy/chemotherapy and surgery. * Use of strong inhibitors or inducers of CYP3A, CYP2C8 and UGT1A1. * Pregnant or breastfeeding women, or subjects of childbearing age who refuse contraception. * Patients with poor cognitive abilities who are unable to answer questions, fill out questionnaires, or have mental disorders. * Patients who do not meet the inclusion criteria; patients who meet the inclusion criteria but are not suitable to participate in this trial judged by the investigator.