Bacillus Calmette-Guérin, or BCG, is the standard immunotherapy used to treat Non-Muscle Invasive Bladder Cancer (NMIBC) after the initial tumor is surgically removed. This treatment involves introducing a weakened, live bacterium into the bladder to stimulate a localized immune response against residual cancer cells. Because NMIBC has a high tendency to return, successful long-term management relies on a sustained approach, often referred to as “maintenance” therapy. This schedule extends the protective effects of the treatment far beyond the initial phase to secure the best possible outcome.
Induction Therapy and the Need for Maintenance
BCG treatment is fundamentally divided into two stages. The first stage is the induction course, which typically consists of six weekly instillations of the drug directly into the bladder. This initial phase is designed to establish a strong immune reaction and immediately eliminate any microscopic cancer cells remaining after surgery.
Following the initial six weeks, treatment transitions into the maintenance phase to reinforce the immune response over time. The induction course alone is often insufficient for long-term tumor control, especially in high-risk patients. Maintenance therapy significantly reduces the chance of the cancer recurring and, more importantly, lowers the risk of the disease progressing to a muscle-invasive stage.
Specific Timing of the Standard Maintenance Schedule
The standard maintenance schedule, often based on the widely recognized Southwest Oncology Group (SWOG) protocol, spans three years for patients with high-risk NMIBC. The treatment is not continuous but is given in short bursts to keep the immune system primed. Each maintenance course consists of three weekly doses, similar to the induction phase, but they are spaced out over months and years.
The first two maintenance courses are typically scheduled at three and six months following the completion of induction therapy. After six months, the schedule transitions to an every-six-month pattern. These subsequent three-dose courses occur at 12, 18, 24, 30, and 36 months from the start of induction, maximizing the treatment’s efficacy over the full three-year period.
Strict adherence to this specific timing is directly linked to the best outcomes in preventing recurrence and progression. This three-year protocol is a standard guideline, but a patient’s individual schedule may be modified by their physician based on their specific risk stratification. For instance, intermediate-risk patients may only require a one-year maintenance schedule, while high-risk patients are advised to complete the full three years.
Managing Expected Treatment Side Effects
Patients undergoing BCG maintenance therapy should anticipate experiencing certain side effects, as the treatment creates a powerful inflammatory immune response within the bladder. The most common localized effects are symptoms of cystitis, including increased urinary frequency, urgency, and burning during urination. These symptoms often begin shortly after the instillation and typically persist for 24 to 48 hours.
Mild blood in the urine (hematuria) is also frequent due to bladder lining irritation. To mitigate these local symptoms, increasing fluid intake immediately following the procedure is recommended to flush the bladder. Over-the-counter pain relievers can also be used for discomfort, but patients should consult their care team before taking anti-inflammatory medications.
Systemic side effects, which feel much like the flu, are also common because the treatment activates the immune system. Patients may experience low-grade fever, chills, fatigue, and muscle or joint aches, usually resolving within two days. A persistent fever above 101.5 degrees Fahrenheit or flu-like symptoms lasting longer than 72 hours should prompt an immediate call to the doctor, as these may indicate a serious systemic infection.
Criteria for Discontinuing or Altering Therapy
The standard maintenance schedule is designed to run for three years, but therapy may be stopped, shortened, or modified for several reasons. The most positive reason for cessation is the successful completion of the full protocol without cancer recurrence detected during regular surveillance cystoscopies. The long-term risk reduction benefit has been achieved.
The primary reason for treatment alteration or discontinuation before three years is patient intolerance or severe side effects. The intense inflammatory response can lead to conditions like BCGitis, where bladder inflammation becomes too severe or chronic, forcing a halt to instillations. In these cases, the physician must weigh the risk of toxicity against the benefit of continuing therapy.
Alternatively, the maintenance schedule must be stopped if cancer recurs or progresses despite treatment. If high-grade tumors return or the disease progresses to a deeper stage, the treatment is considered ineffective, or “BCG-unresponsive.” This outcome necessitates moving toward alternative, more aggressive treatments, which may include chemotherapy or radical cystectomy (surgical removal of the bladder).