A Bladder-Sparing Treatment Strategies of Large-Volume Non-Muscle-Invasive Bladder Cancer

Inclusion Criteria: \- Diagnosis of large non-muscle-invasive bladder cancer: Tumor size ≥5 cm, ≤3 tumors, pre-TURBT VI-RADS score \<3, or biopsy confirms non-muscle-invasive urothelial carcinoma. Ability to tolerate neoadjuvant chemotherapy and immunotherapy: Sufficient heart, bone marrow, liver, and kidney function (according to clinical trial center normal values), no severe hematologic abnormalities or organ dysfunction (heart function 0-2, WBC ≥3.5×10⁹/L, neutrophil count ≥1.5×10⁹/L, PLT ≥75.0×10⁹/L, HGb ≥80 g/L; liver function: total bilirubin ≤1.5×ULN, AST and ALT ≤2.5×ULN; kidney function: creatinine ≤1.5×ULN, or GFR ≥60 ml/min if creatinine \>1.5×ULN). ECOG performance status: 0 or 1. No history of other malignancies. Able to receive regular mitomycin C bladder instillation therapy after TURBT. Male or female, aged ≥18 and \<80 years. Voluntary participation with written informed consent, and ability to understand and comply with study requirements, including regular follow-up. Exclusion Criteria: * Preoperative imaging assessment with VI-RADS ≥3. Postoperative pathology showing non-urothelial carcinoma (e.g., adenocarcinoma, squamous cell carcinoma, small cell carcinoma, or mixed tumors), or urothelial carcinoma ≥T2. Presence of lymph node and/or distant metastases. Allergy or hypersensitivity to treatment drugs, or patients with autoimmune diseases. Any condition deemed by the investigator to potentially harm the participant or prevent them from meeting or fulfilling study requirements.