The goal of this observational study is to assess the safety and efficacy of trimodality bladder - sparing therapy in high - risk NMIBC patients. The main questions it aims to answer are:

Is trimodality therapy safe and effective in the short term for high - risk NMIBC patients? What is its long - term effectiveness in terms of EFS, OS, and BI - EFS? How does it affect patients' QOL? Participants will be high - risk NMIBC patients receiving trimodality therapy at Peking University First Hospital. They will be observed to evaluate the therapy's effectiveness and impact on QOL using relevant assessment criteria and QOL scores.

Inclusion Criteria:

Histologically confirmed NMIBC (Ta Tis T1).

≥2 recurrences after transurethral resection, or lack of response/intolerance to intravesical therapy (e.g., BCG).

Refusal of radical cystectomy and choice of TMT for bladder preservation. Aged ≥18 years. Signed informed consent. ECOG performance status of 0-2.

Adequate organ function for chemoradiotherapy:

Hematology: Absolute neutrophil count ≥1.5×10⁹/L, platelets ≥100×10⁹/L, hemoglobin ≥90 g/L.

Liver function: Total bilirubin ≤1.5×ULN, ALT and AST ≤2.5×ULN (≤5×ULN if hepatic metastasis is present).

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.

High-risk patients with NMIBC who have a strong desire to preserve their bladder actively choose to receive TMT bladder treatment instead of radical resection.