BCG Treatment for Cancer

Introduction

What is BCG Treatment?

• What type of immunotherapy is it?
• How does BCG immunotherapy work?

Bacillus Calmette-Guerin (BCG) treatment is an immunotherapy treatment which uses a weakened strain of the aerobic bacterium Mycobacterium bovis and was originally developed as a vaccine for tuberculosis.¹ The BCG vaccine is a form of intravesical immunotherapy which has been developed due to the high recurrence rate and progression rate of non-muscle invasive bladder cancer.² For the BCG therapy to work effectively the BCG must be in direct contact with the cancer cells, which is why this treatment is administered by inserting a catheter directly into the bladder of the patient.³  Immunotherapy is an effective treatment against a huge array of diseases, including cancers, as it aims to stimulate the patient’s immune system to prevent or delay tumour progression. It may work by stimulating T effector lymphocytes to target cancer cells, and therefore result in tumour regression. 

BCG therapy works by stimulating the antitumour activity of immune cells, specifically T cells, and works in multiple steps. The first step is BCG attachment to the urothelium – the tissue that lines the urinary tract. Most bladder cancers occur in this type of tissue as it has a high “turnover rate” because the cells are regenerated more often, and are therefore more at risk of uncontrolled cell growth which can lead to a tumour. BCG attaches to the urothelium through fibronectin. It is internalized by urinary tract cells and then recognized and captured by the immune cells present in the bladder. When captured, these cells become antigen-presenting cells and release cytokines which upregulate the major histocompatibility complex II (MHCII); this, in turn, leads to the recruitment of T lymphocytes to the site of infection which includes CD8 T cells and NK T cells. These cells produce cytokines including tumour necrosis factor (TNF)-alpha and interferon-gamma which are used to kill the bladder cancer cells. The immunotherapy treatment is therefore effective because it boosts the patient’s immune system, creating a cytotoxic environment for bladder tumour cells and killing them, resulting in tumour regression.^2,4

When is BCG Treatment used?

• At what stage of cancer is it used?
• How many times a week do you need BCG immunotherapy?

BCG treatment is likely used two weeks after transurethral resection of a bladder tumour (TURBT), a surgery which removes non-invasive muscle bladder cancer.⁵ Using the BCG vaccine treatment can prevent the return of this type of bladder cancer. The treatment can be used to treat early-stage bladder cancer, advanced bladder cancer and non-invasive bladder cancer and is administered once a week for 6 weeks.⁶

Administering BCG treatment

What happens during the treatment process (before, during, and after treatment)

Before receiving BCG treatment, patients must limit their fluid intake the 6 hours before the procedure, as drinking less will reduce the amount of urine produced. This is important as a high amount of liquid in the bladder can dilute the concentration of the BCG and therefore, the correct dosage won’t be administered. Local anaesthesia is then administered to numb the area and make the procedure less painful. 

To administer the BCG therapy, first, a catheter is placed directly into the bladder. The bladder is drained of any urine present and then a diluted solution of BCG is introduced directly into the bladder through the catheter to ensure the BCG solution reaches the bladder cancer cells directly. The BCG will remain in the bladder for 2 hours before the patient can urinate to remove the BCG solution from their body.⁶ This is not considered a painful procedure but some patients do find it uncomfortable. 

After the BCG treatment, the patient should sit down to pass urine and clean their genital area to remove any potential BCG that remained on their skin following urination. Once finished, wash your hands thoroughly and place undiluted bleach in the toilet bowl and let sit for 15 minutes before flushing to disinfect the bathroom. For the days after the treatment, it is common to drink 2 litres of fluid a day in as this helps remove the drug from the bladder.⁵

Side effects of BCG Treatment

Common side effects of the BCG treatment may include:

• urinating more often
• urinary tract infections
• experiencing burning or pain during urination 
• blood in the urine
• mild fever
• tiredness
• vomiting
• chills

These side effects tend to last a couple of days following the intravesical BCG intervention, where the effects appear normally after the third intervention and worsen after each administration.⁷ A much less common side effect is that the BCG may spread through the body and reach other organs.⁸ If the side effects worsen or persist, contact your doctor. 

Can you have sex after BCG Treatment?

There is a risk that men undergoing Bacillus Calmette-Guerin treatment can pass on BCG during sexual intercourse. To prevent this from happening, patients should refrain from sexual activity for 48 hours after each treatment and should use protection during sexual relations at all times during the treatment course and for 6 weeks after the treatment has ended.⁹ If you are a woman undergoing treatment, your partner should wear protection too. 

Is BCG the best treatment option for bladder cancer?

The use of BCG treatment to treat bladder cancers is considered to have a 90% success rate and has been shown to have eradicated bladder cancer in 70% of cases.¹⁰ This supports that BCG is a great treatment option for bladder cancer, especially following TURBT surgery. Additionally, immunotherapy is becoming a novel focus point in the treatment as it boosts the patient's immune system and is, therefore, less invasive. 

Summary

Overall, BCG therapy is a treatment with a very high success rate and is often used to treat bladder cancer. The treatment cycle usually only lasts 6 weeks and should not be very painful. Patients may experience uncomfortable symptoms and should contact a medical expert if these problems persist.