Radical Nephroureterectomy With vs Without Template Lymph Node Dissection in High-Risk Upper Tract Urothelial Carcinoma (T-LND UTUC)

Inclusion Criteria: * Signed written informed consent form (ICF). * Age \> 18 years at the time of ICF signing. * Clinical diagnosis of unilateral Upper Tract Urothelial Carcinoma (UTUC) by imaging (enhanced CT or MRI) and/or ureteroscopic biopsy/urinary cytology, and scheduled to undergo Radical Nephroureterectomy (RNU). * Clinical assessment indicating that the tumor and regional lymph nodes are completely resectable, with at least one of the following high-risk features: 1. Locally advanced: Preoperative imaging assessed as cT2 stage or higher (i.e., tumor invades muscularis propria or deeper). 2. High-grade: Preoperative ureteroscopic biopsy pathology confirmed as high-grade urothelial carcinoma (or with squamous differentiation/sarcomatoid differentiation). 3. Moderate or severe hydronephrosis: Ipsilateral moderate or severe hydronephrosis due to tumor obstruction. 4. Large tumor size: Imaging measures maximum tumor diameter \> 2 cm. 5. cN1: Imaging suggests regional lymph node short-axis diameter \> 1 cm, and the investigator judges it to be resectable. * Presence of at least one measurable lesion according to RECIST v1.1 criteria. * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. * Adequate organ function meeting the following requirements (without use of any blood components or colony-stimulating factors within 14 days): Bone marrow function: Neutrophils ≥ 1,500/mm³, Platelets ≥ 100,000/mm³, Hemoglobin ≥ 9 g/dL (5.6 mmol/L). Renal function: Serum creatinine ≤ 1.5 mg/dL and/or Creatinine clearance ≥ 60 mL/min. Liver function: Total bilirubin ≤ 1.5 × ULN, AST \& ALT ≤ 1.5 × ULN. * For women of childbearing potential (WOCBP): Must agree to use a highly effective medically approved contraceptive method during the treatment period and for 3 months after treatment ends. A negative serum or urine pregnancy test within 7 days before enrollment is required; must be non-lactating. For non-sterilized male patients: Must agree to use effective contraception with their partner during the treatment period and for 3 months after treatment ends. * Subject voluntarily joins the study, has good compliance, and agrees to undergo safety and survival follow-up. Exclusion Criteria: * Previous receipt of any anti-tumor therapy for UTUC, including chemotherapy, radiotherapy, immunotherapy, or targeted therapy. * History or concurrent presence of muscle-invasive bladder urothelial carcinoma. * Preoperative imaging assesses regional lymph nodes as unresectable: lymph nodes fused into a massive conglomerate, or fully encasing the abdominal aorta/inferior vena cava/pelvic vessels preventing safe separation. * Known bilateral UTUC or hereditary diseases that definitively increase the risk of contralateral upper tract tumors, such as Lynch Syndrome. * Diagnosis of other active malignancies within the past 5 years (except for adequately treated basal cell carcinoma, squamous cell carcinoma of the skin, or carcinoma in situ of the cervix which have been cured and show no recurrence within 5 years). * Presence of any active autoimmune disease or history of autoimmune disease. * Current use of immunosuppressants for immunosuppressive purposes, continued within 2 weeks prior to enrollment. * Poorly controlled cardiac clinical symptoms or diseases. * Coagulation abnormalities or bleeding tendency. * Presence of specific active gastrointestinal conditions or uncontrolled tumor bleeding. * History of significant bleeding, hemoptysis, or thromboembolic events within specified timeframes. * Active infection or unexplained fever \> 38.5°C during screening or before the first dose. * Occurrence of abdominal fistula, gastrointestinal perforation, or intra-abdominal abscess within 4 weeks prior to surgery. * History or current objective evidence of pulmonary fibrosis, interstitial pneumonia, pneumoconiosis, radiation pneumonitis, drug-related pneumonia, severely impaired pulmonary function, etc. * Congenital or acquired immunodeficiency. * Participation in another clinical study within 1 month prior to enrollment, or potential receipt of other systemic anti-tumor therapy during the study period. * Known history of psychotropic drug abuse, alcohol abuse, or drug use. * Inability or unwillingness to bear the out-of-pocket costs of examinations and treatments. * Any other condition deemed by the investigator to make the subject unsuitable for participation.