Intravesical therapy is a medical treatment for bladder cancer that involves delivering liquid medication directly into the bladder through a catheter. This localized approach allows the drug to have direct contact with the cancer cells lining the bladder wall. The procedure is designed to maximize the drug’s effect at the tumor site while minimizing systemic exposure.
The Rationale for Localized Treatment
This targeted delivery system is primarily used to treat non-muscle invasive bladder cancer (NMIBC), which accounts for the majority of new bladder cancer diagnoses. In this stage, the cancer cells remain confined to the inner lining of the bladder and have not grown into the deeper muscle layer. Treating cancer at this localized stage is important because NMIBC has a high rate of recurrence.
The intravesical method is a strategic choice because it achieves a very high concentration of the medication precisely where the cancer is located. By contrast, systemic treatments, such as oral or intravenous chemotherapy, circulate throughout the entire body, reaching much lower concentrations in the bladder. The direct application of the drug is more effective against the surface-level cancer cells and significantly reduces the systemic side effects commonly associated with traditional chemotherapy.
Categorization of Intravesical Agents
The medications used in this therapy fall into two main categories: immunotherapy agents and chemotherapy agents. Immunotherapy works by stimulating the body’s own defense mechanisms inside the bladder to attack the cancer cells. The most widely used agent for this purpose is Bacillus Calmette-Guérin (BCG), a weakened strain of Mycobacterium bovis, which is related to the bacteria that causes tuberculosis.
When BCG is instilled into the bladder, it attaches to the bladder wall and triggers an intense, localized immune response. This activation recruits various immune cells, such as T-cells and macrophages, which then recognize and destroy the malignant cells. BCG is considered the standard treatment for intermediate- and high-risk NMIBC because of its success in reducing the risk of cancer progression.
Chemotherapy agents, on the other hand, are cytotoxic drugs that directly kill actively dividing cancer cells by interfering with their DNA synthesis. Common chemotherapeutic agents used intravesically include Mitomycin C, Gemcitabine, and Epirubicin. These drugs are often used immediately following a surgical procedure to remove the tumor or as an alternative when immunotherapy is not suitable or has failed. For instance, Mitomycin C may be administered as a liquid or in a gel formulation that is designed to stay in the bladder for an extended period, increasing its contact time with the tumor cells.
The Administration Procedure
The procedure for administering intravesical therapy is typically performed in an outpatient clinic setting. The patient is first asked to empty their bladder completely to ensure the medication is not immediately diluted by residual urine. To introduce the liquid agent, a thin, flexible tube called a catheter is gently inserted through the urethra and into the bladder.
Once the catheter is in place, the pre-mixed liquid medication is slowly instilled into the bladder. The catheter is then removed, or sometimes clamped, and the patient is asked to retain the liquid for a specified period, known as the dwell time. This retention time is typically set for one to two hours, which allows the medication sufficient time to penetrate the bladder lining. To maximize the effectiveness of the treatment, patients may be advised to limit fluid intake for several hours before the procedure. After the designated dwell time has elapsed, the patient voids the solution into a toilet, often with specific safety precautions to prevent exposure to the active drug.
Expected Patient Experience and Treatment Schedule
Patients undergoing intravesical therapy often experience localized side effects that are confined to the bladder and urinary tract. Common symptoms include a burning sensation or discomfort during urination, an increased urge to urinate, and having to urinate more frequently. Some may notice a small amount of blood in their urine or see tiny pieces of the bladder lining slough off.
Patients receiving BCG immunotherapy may also experience flu-like symptoms, such as a low-grade fever, aches, chills, and fatigue, which usually resolve within two to three days after the treatment. The treatment follows a structured schedule, beginning with an induction phase, which typically involves weekly treatments for six weeks. If this initial phase is successful, a maintenance phase may be recommended to prevent recurrence, which can involve periodic treatments over one to three years.