BCG and Mitomycin C Intravesical Therapy

What is intravesical therapy?

Intravesical therapy means delivering a drug directly into the bladder through a catheter, rather than by mouth or by injection into the bloodstream. Because the drug acts locally within the bladder, this approach allows a high concentration of the agent to reach the bladder lining while minimising systemic side effects.

Two main agents are used in urology:

BCG (Bacillus Calmette-Guérin) is a biological immunotherapy. It is a modified, weakened strain of the bacterium that causes tuberculosis, which is used here to stimulate the immune system within the bladder to attack and destroy residual cancer cells. BCG is the standard treatment for intermediate- and high-risk non-muscle-invasive bladder cancer (NMIBC) following TURBT.

Mitomycin C (MMC) is a cytotoxic chemotherapy agent. Given as a single instillation immediately after TURBT, it reduces the likelihood of early tumour recurrence by destroying free-floating tumour cells that may have been dispersed during the resection. It is also used as a six-week course for lower-risk non-muscle-invasive tumours.

Who receives intravesical treatment?

After TURBT, the pathology report categorises the bladder tumour by grade and depth of invasion. Non-muscle-invasive bladder cancer (NMIBC) — where the tumour has not grown into the muscle layer of the bladder — is managed with intravesical therapy rather than surgery to remove the bladder.

The risk of recurrence and progression varies by tumour characteristics:

• Low-risk NMIBC: A single dose of MMC immediately after TURBT, followed by cystoscopic surveillance.
• Intermediate-risk NMIBC: A course of MMC or BCG instillations.
• High-risk NMIBC: BCG induction course followed by a maintenance schedule, which significantly reduces the risk of recurrence and progression to muscle-invasive disease.

What to expect: before, during, and after

Before each instillation

A urine test is checked. If infection is present, the instillation is postponed, as introducing BCG or MMC into an infected bladder is not safe and can cause severe side effects. You should not have diuretics (water tablets) before the appointment if possible and should try to avoid drinking excessively in the hours beforehand so the drug is not immediately diluted by urine.

During the procedure

A small urinary catheter is passed through the urethra into the bladder — usually without anaesthetic or with minimal discomfort. The drug is administered through the catheter, the catheter is removed, and you are asked to retain the liquid in the bladder for the prescribed period before voiding normally.

After the procedure

Urinary frequency, urgency, and burning are common for a few days following each BCG instillation. Hygiene precautions are recommended when passing urine for six hours after BCG instillation (sitting down, voiding into toilet with bleach or vinegar, and washing hands thoroughly), to deactivate any bacteria that may be excreted. For MMC, standard hygiene is sufficient.

Monitoring and long-term follow-up

Follow-up cystoscopy is arranged at regular intervals after intravesical treatment — typically at three months initially, then at intervals determined by risk stratification. This surveillance is essential to detect any tumour recurrence at an early stage, when further TURBT or adjustment of the instillation schedule can be undertaken.

Full attendance at scheduled instillations is important: the protective effect of BCG in particular depends on the immune response being adequately stimulated over the full course of treatment. If a reaction occurs that requires a dose to be delayed or modified, this is managed clinically.