Non-muscle-invasive bladder cancer (NMIBC) accounts for approximately 75% of newly diagnosed bladder cancers and is characterized by a high risk of recurrence and progression. Current guidelines recommend that patients with stage T1 NMIBC undergo a second transurethral resection of bladder tumor (re-TURBT) within 2-6 weeks after the initial surgery to remove residual tumor, confirm staging, and obtain additional pathological information. However, the benefits of routine re-TURBT for all high-risk patients remain controversial, as many patients may not have residual disease, while the procedure carries surgical and anesthetic risks, physical and psychological burden, and additional healthcare costs.

Urine tumor DNA (utDNA) refers to DNA fragments shed by tumor cells into urine. It can be detected using molecular assays with high sensitivity and specificity, offering a non-invasive method for bladder cancer diagnosis and surveillance. Previous studies have shown that positive utDNA results after initial TURBT may be associated with residual disease and higher recurrence risk.

This multicenter, randomized controlled trial aims to evaluate whether utDNA testing can accurately identify NMIBC patients who are most likely to benefit from re-TURBT, thereby guiding the decision to perform the procedure. The goal is to optimize patient selection for re-TURBT, reduce unnecessary surgeries, and improve patient quality of life while maintaining oncologic safety.

Inclusion Criteria:

Participants must meet all of the following criteria to be eligible for the study:

1. Male or female, aged 18 years or older.

2. Histologically confirmed non-muscle-invasive bladder tumor, with no evidence of muscle-invasive bladder cancer or metastatic disease.

3. Histologically confirmed urothelial carcinoma of the bladder or bladder tumor with urothelial carcinoma as the predominant component (>50%).

4. At least one of the following conditions:

   1. Incomplete initial transurethral resection of bladder tumor (TURBT) or suspected incomplete resection.
   2. Absence of detrusor muscle in the initial TURBT pathological specimen (except for low-grade Ta stage tumors or carcinoma in situ [CIS]).
   3. T1 stage tumor.

5. Willingness to provide a 50 mL urine sample between 2-6 weeks after the initial TURBT and prior to re-TURBT.

6. Willingness to provide tumor tissue samples for pathological examination.

7. Willingness to undergo genetic testing required for the trial.

Exclusion Criteria:

1. Contraindications to transurethral resection of bladder tumor (TURBT).
2. Concurrent malignancy of the upper urinary tract (ureter or renal pelvis).