Intravesical Bacillus Calmette-Guérin (BCG) is an immunotherapy treatment used primarily for early-stage (non-muscle-invasive) bladder cancer. It involves directly instilling a weakened strain of the Mycobacterium bovis bacteria (the same organism used in the TB vaccine) into the bladder via a catheter.
How It Works:
- BCG stimulates the immune system, triggering an inflammatory response that helps destroy cancer cells in the bladder lining.
- It is most effective for carcinoma in situ (CIS) and high-grade Ta/T1 tumors to prevent recurrence and progression.
Administration:
- A catheter is inserted into the bladder.
- BCG solution is infused and retained for 1–2 hours.
- The patient then voids the solution naturally.
- Treatment is typically given once weekly for 6 weeks (induction therapy), sometimes followed by maintenance therapy (additional doses over several months).
Side Effects:
- Common: Urinary frequency, urgency, dysuria (painful urination), hematuria (blood in urine), fatigue, low-grade fever.
- Serious (rare): BCG infection (systemic), high fever, persistent flu-like symptoms, granulomatous prostatitis, or contracted bladder.
Contraindications:
- Active urinary tract infection (UTI).
- Immunosuppression (e.g., HIV, chemotherapy).
- Gross hematuria or traumatic catheterization.
- History of BCG sepsis.
Efficacy:
- Reduces recurrence by ~50–70% and progression risk in high-risk non-muscle-invasive bladder cancer.
- Considered the gold standard for high-grade tumors and CIS.
Mechanism:
BCG attaches to the bladder wall, recruiting immune cells (T-cells, macrophages, cytokines) that attack both bacteria and cancer cells.