Observational Clinical Study of Patients With Muscle - Invasive Bladder Cancer Undergoing Bladder Preservation Therapy After Neoadjuvant Therapy

Inclusion Criteria: Histopathologically confirmed bladder cancer (T2-T4aN0-2M0, 8th edition AJCC staging). Underwent bladder - sparing TMT following neoadjuvant therapy (ADC, immunotherapy, or chemotherapy). Aged ≥18 years. Signed an informed consent form. Good general condition with ECOG performance status of 0-2. Adequate organ function for chemoradiotherapy: (1) Hematology: Absolute neutrophil count ≥1.5×10⁹/L, platelets ≥100×10⁹/L, hemoglobin ≥90 g/L. (2) Liver function: Total bilirubin ≤1.5×ULN, ALT and AST ≤2.5×ULN (≤5×ULN if hepatic metastasis is present). (3) Renal function: Creatinine clearance ≥30 mL/min (via Cockcroft-Gault formula). Exclusion Criteria: Distant metastasis (M1). Other malignancies (except cured basal cell carcinoma or cervical carcinoma in situ). Severe cardiovascular disease (uncontrolled heart failure, unstable angina, myocardial infarction, etc.). Severe hepatic/renal dysfunction intolerance to chemoradiotherapy. Mental illness/cognitive impairment unable to comply with the study. Allergy to chemoradiotherapy drugs. Pregnant or breastfeeding women. Previous pelvic radiotherapy.