T1G3 bladder cancer is a heterogeneous disease with a high risk of disease persistence after the first TUR-B, understaging, disease progression, bladder removal, and mortality.

Current risk stratification is insufficient and needs improvement. Ct-DNA could identify patients with disease persistence, progression and could monitor and tailor therapy. It might improve patient risk stratification, avoiding under- and overtreatment, reducing morbidity and mortality.

Primary objective is to investigate the detectability of ct-DNA in T1G3 urothelial bladder cancer patients and build a biobank through collection of different sample types (urine, plasma) in T1G3 bladder cancer patients which allows future retrospective testing.

Inclusion Criteria:

• patients > 18 years of age, able to give informed consent as documented by signature,
• patients with a cystoscopically proven bladder cancer, suspicious for T1 stage, who will undergo TUR-B

Exclusion Criteria:

• Patients with metastases or concomitant upper tract tumor at diagnosis will
• Patients with non T1 G3 cancers
• Patients with upstaging, either at re-TUR-B or after immediate radical cystectomy
• Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia, etc.
• Vulnerable persons (e.g. < 18y of age, unable to consent to the study)

Patients with a proven T1G3 Bladder Cancer