Phase II Study of Oral Metformin for Intravesical Treatment of Non-muscle-invasive Bladder Cancer

This trial is testing whether metformin — a common diabetes medication — delivered directly into the bladder through a catheter (rather than taken by mouth) can help prevent the return of early-stage bladder cancer after it has been removed by cystoscopy. **You may be eligible if...** - You are over 18 years old - You have been diagnosed with early-stage bladder cancer (stage Ta or T1, low grade) that is new or has come back - You have between 1 and 5 bladder tumors - At least one tumor measures between 0.5 cm and 1.0 cm in size - Your kidney and liver function meet the required levels **You may NOT be eligible if...** - Your cancer is suspected to be high-grade or deeply invasive into the bladder wall - You have more than 5 bladder tumors - A mass was felt in the bladder during examination under anesthesia - Your kidney function is below the required level - You have certain liver conditions Talk to your doctor to see if this trial is right for you.