What is BCG (Bacillus Calmette-Guerin) immunotherapy for bladder cancer?

How to Explain BCG to a Patient with Bladder Cancer

BCG (Bacillus Calmette-Guérin) is a live, weakened bacteria originally developed as a tuberculosis vaccine that we instill directly into your bladder through a catheter to activate your immune system to recognize and destroy bladder cancer cells. 1

What BCG Is and How It Works

• BCG is a live, attenuated strain of Mycobacterium bovis (a bacteria related to tuberculosis) that has been used to treat bladder cancer since 1976 2
• When instilled into your bladder, BCG bacteria are internalized by the cells lining your bladder wall, triggering a powerful immune response 2
• This immune activation recruits multiple types of immune cells—including neutrophils, monocytes, macrophages, T cells, B cells, and natural killer cells—to attack cancer cells 2
• BCG is the most effective intravesical (inside the bladder) treatment available and is the only therapy proven to not just prevent cancer recurrence but also reduce the risk of your cancer progressing to a more advanced stage 3, 4

Why You Need BCG Based on Your Cancer Risk

Your doctor has determined your bladder cancer risk category, which dictates whether BCG is appropriate:

High-Risk Disease (T1 tumors, high-grade Ta, or carcinoma in situ)

• BCG induction plus 3-year maintenance therapy is the standard of care 1
• BCG reduces recurrence rates by 24% compared to surgery alone and reduces 72-month recurrence rates by 30% compared to chemotherapy 3
• This is the only treatment proven to reduce disease progression, not just recurrence 3

Intermediate-Risk Disease (multiple or recurrent low-grade tumors)

• BCG induction with 1-year maintenance is recommended if you have 3-4 risk factors (multiple tumors >3cm, recurrence within 1 year, frequent recurrences >1 per year) 1
• BCG with maintenance reduces recurrences by 31% compared to surgery alone 3

Low-Risk Disease

• BCG is typically not recommended; observation or single-dose chemotherapy is preferred 1

The Treatment Schedule

Induction Phase (Initial 6 Weeks)

• You will receive BCG instillations once weekly for 6 consecutive weeks 5
• Each treatment involves inserting a catheter into your bladder, instilling the BCG solution, and holding it in your bladder for approximately 2 hours 2

Maintenance Phase (Critical for Success)

• Maintenance therapy is crucial—a single 6-week induction course alone is suboptimal 5
• The evidence-based SWOG schedule involves additional treatments at 3,6,12,18,24,30, and 36 months (3 weekly instillations at each timepoint) 1, 3
• Studies show that even just 3 additional weekly treatments at week 12 increase complete response rates from 70% to 82% 5
• For high-risk disease, you need the full 3-year maintenance regimen 1

What to Expect: Side Effects

Common Side Effects (Occur in Most Patients)

• Dysuria (painful urination), urinary frequency, and urgency 2
• Flu-like symptoms including fever, malaise, and fatigue 2
• These symptoms are typically mild, transient, and indicate your immune system is responding 2

Serious but Rare Complications

• BCG sepsis (bloodstream infection) can occur if BCG enters your bloodstream, often due to hypersensitivity 5
• If you develop high fever (>103°F), severe flu-like symptoms lasting >48 hours, or difficulty breathing, seek immediate medical attention 5
• Treatment for BCG sepsis requires isoniazid 300mg, rifampicin 600mg, and prednisolone 40mg daily 5

Important Safety Precautions

• Do not receive BCG if you have a suspected bladder perforation, extensive resection with concern for extravasation, or visually apparent muscle-invasive disease 3
• Avoid BCG if you are immunocompromised 1

When BCG Doesn't Work

• If your high-grade cancer recurs within 6 months after completing two induction courses or induction plus maintenance, BCG has failed and you should not receive more BCG 3
• At this point, you need either bladder removal surgery (cystectomy) or enrollment in a clinical trial 3
• For BCG-unresponsive disease with carcinoma in situ, nadofaragene firadenovec (a gene therapy) is FDA-approved and shows 53.4% complete response at 3 months, offering an alternative to cystectomy 3

Why BCG Is Superior to Other Options

• BCG with maintenance is superior to mitomycin C (chemotherapy) alone in preventing recurrence in high-risk patients, with a 30% reduction in 72-month recurrence rates 3
• For carcinoma in situ specifically, BCG is recommended in most guidelines as the high-risk standard 1
• BCG has been shown to decrease the need for cystectomy and prolong survival in controlled trials 5

Critical Points to Remember

• You must complete the full maintenance schedule—stopping after induction alone significantly reduces your chance of cure 5
• BCG toxicity is slightly greater than chemotherapy, but the superior efficacy in preventing progression justifies this trade-off for high-risk disease 4
• Your response to BCG can be monitored through cystoscopy and urine cytology at scheduled intervals 1
• BCG remains the most effective intravesical agent available and has over 40 years of proven efficacy 6