Bacillus Calmette-Guérin (BCG) is a weakened bacterium, originally developed as a vaccine against tuberculosis. It is now widely recognized as an effective immunotherapy for early-stage bladder cancer. This treatment leverages the body’s own immune system to target and eliminate cancer cells in the bladder lining, making it a common and successful approach.
How BCG Works Against Bladder Cancer
When BCG is introduced into the bladder, it attaches to the cells lining the bladder, including cancer cells, and becomes internalized within them. This interaction acts like a signal, prompting the bladder lining and cancer cells to release various signaling molecules known as cytokines and chemokines. These molecules attract a significant influx of immune cells to the bladder.
The activated immune cells, including CD4+ and CD8+ T-lymphocytes, natural killer cells, granulocytes, and macrophages, recognize the presence of BCG. These specialized cells then identify and attack the nearby cancer cells. The immune response leads to the destruction of tumor cells through mechanisms like direct cytotoxicity and the release of soluble factors. BCG also directly induces programmed cell death in cancer cells.
The BCG Treatment Process
BCG therapy involves intravesical instillation, where the liquid BCG solution is delivered directly into the bladder. A thin, flexible tube called a catheter is temporarily inserted through the urethra to allow the solution to enter the bladder. Once the solution is instilled, the catheter is removed, and the patient is asked to hold the liquid in their bladder for one to two hours.
The initial phase of treatment, known as the induction course, usually consists of weekly instillations for six consecutive weeks. Following this, if the treatment proves effective, a maintenance course may be recommended to prevent cancer recurrence. Maintenance therapy schedules can vary, but often involve less frequent treatments, such as three weekly instillations at three, six, and twelve-month intervals, potentially continuing for up to three years.
After each treatment, specific precautions are advised for handling urine for at least six hours due to the presence of live bacteria from the BCG. Patients are encouraged to sit when urinating to prevent splashing and to add two cups of undiluted bleach to the toilet after each use, waiting 15-20 minutes before flushing. Any clothing or surfaces that come into contact with urine should be washed immediately and separately to minimize exposure.
Patient Candidacy and Efficacy
BCG immunotherapy is primarily used for individuals diagnosed with non-muscle invasive bladder cancer (NMIBC). This type of cancer is confined to the inner lining of the bladder and has not grown into the deeper muscle layer. It is particularly effective for specific stages of NMIBC, including Ta, T1, and Carcinoma in Situ (CIS), which represents a high-grade, flat lesion.
The success rates of BCG in preventing cancer recurrence are generally high, making it a preferred option for many patients. While highly effective, the treatment does not guarantee universal success, and some patients may still experience recurrence or progression. Regular follow-up examinations, such as cystoscopies, are conducted to monitor the bladder’s response to treatment and detect any signs of returning cancer.
Managing Side Effects
Patients undergoing BCG therapy commonly experience localized side effects within the bladder, often indicative of the immune system actively responding to the treatment. These can include discomfort, a burning sensation during urination, or an increased frequency of needing to urinate. Some individuals may also develop flu-like symptoms, such as a low-grade fever, chills, or general fatigue, usually within a few hours to a day after treatment.
While less common, more serious systemic infections can rarely occur if the BCG bacteria spread beyond the bladder. Contact a healthcare provider immediately if severe symptoms arise, such as a high fever lasting more than 48 hours, persistent pain, or signs of a widespread infection. To manage common side effects, staying well-hydrated can help dilute the urine and reduce bladder irritation, and doctor-approved over-the-counter pain relievers may be used to alleviate discomfort.