Introduction
Studies show that bladder cancer ranks among the fifth most common type of cancer in the United States. An ideal organ for regional therapy can be the urinary bladder. The urothelium (a specialized transitional epithelium lining the urinary system) has a specialized unit membrane. This acts as a protective barrier and limits the transmission of molecules into the systemic circulation. In drugs with smaller molecules, less than five percent is absorbed into the systemic absorption. Intravesical therapy aims to help the affected organ get the maximum treatment benefit while lesser absorption happens in the systemic circulation.
What Is Intravesical Therapy?
Intravesical therapy is used mainly in the early stages of bladder cancer when cancer is still in the bladder's lining. Cytotoxic agents (drugs used to kill cancerous cells) or immuno-stimulating agents (medicines that can stimulate the immune system by increasing the activity of one of its components) are used to destroy cancerous growth. When drugs are given directly into the bladder, their activity can be seen only in the cells inside the lining of the bladder and does not affect any other cells in any part of the body. This shows that the cancerous cells in the different parts of the body cannot be treated by this method.
When Is Intravesical Therapy Used?
Intravesical therapy is used when it is necessary to limit the effect of the treatment to a particular area without having much impact on systemic circulation. It can be used in:
Management of Non-muscle Invasive bladder Cancer (NMIBC): This is the very early stage of bladder cancer, where cancer has not reached the muscular layer of the bladder wall or the other parts of the body. These cancers are Grade 0 or carcinoma in-situ (limited to the bladder's lining). They can also include Stage 1, where cancer has reached the layer below the bladder's lining. Intravesicular therapy is often used after transurethral resection of bladder tumors (superficial and non-muscle invasive treatment for early stages of cancer). Intravesical chemotherapy might be given within twenty-four hours after the procedure. If further treatments are required, they are scheduled after a few weeks.
Further treatments are decided based on the recurrence rate of cancer, the prior treatment, the cancer response to the treatments given, and other similar factors. Additional therapies might not be required when the cancer is at lower risk. On the other hand, if the condition is risky, intravesical treatment might be required weekly or at a lesser frequency for up to three years.
Treatment of Higher Grade or Invasive Cancers: Higher grade cancers are the ones where the cancerous cells have reached the muscular layer of the bladder. In cases where transurethral resection of bladder tumors is done as the first surgery, intravesical chemotherapy is done as the second treatment within twenty-four hours. But this might not be helpful in high-grade cancers where the cancerous cells might have spread beyond the bladder's inner lining. In cases where surgery cannot be done as the first treatment, chemotherapy or radiation therapy is done as the initial treatment. This is followed by intravesicular immunotherapy can be used if the cancerous growth has reduced to a sufficient size. Very high-grade cancers are not usually treated with intravesical therapy.
What Are the Types of Intravesical Therapy?
There are two main types of intravesical therapy, which includes:
1. Intravesical Immunotherapy: This is a treatment where the body's immune system destroys the cancerous cells.
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Bacillus Calmette Guerin (BCG): This is the most common type of intravesical immunotherapy to treat cancer in the early stages. BCG is the vaccine that is used to treat tuberculosis. When BCG liquid is put into the bladder through the catheter, it activates the immune system. As a result, it destroys the cancerous cells in the bladder. Treatment with the BCG vaccine can cause symptoms like flu, chills, body aches, etc. This can last two to three days after the treatment. The patient might have a burning feeling or urinate frequently. People with weak immunity might have severe infections, and most people may not become sick. Hence this treatment might not be done in such people.
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Nadofaragene firadenovec (Adstriladrin): In this mode of treatment, a virus that contains a gene to make interferon alfa 2b is used. Interferon alfa 2b is an essential protein in the immune system. When a mixture containing this is put into the bladder, the genes are transferred to the bladder's lining. Production of interferon alfa 2b happens, which helps to destroy the cancerous cells. This method is considered gene therapy as a gene is introduced in the procedure. Adstriladrin is used in cancers with a high recurrence rate and cases where BCG is ineffective. Usually, it is done once in three months. While Adstriladrin is used, some people might experience tiredness, bladder spasms, or even blood in the urine. Since a virus is used in this treatment, it may cause severe effects in people with weak immunity. Hence it should be avoided in such individuals.
2. Intravesical Chemotherapy: In chemotherapy, the drugs are placed in the bladder through a catheter. The medications used are capable of killing cancerous cells. These drugs can be given systemically to treat advanced stages of bladder cancer. Intravesical chemotherapy is used when intravesical immunotherapy is not effective. In some cases, the drugs used for chemotherapy are heated before putting in the bladder. Some experts argue that this can increase the action of the drug. If the drug is heated before placing in the bladder, it is called hyperthermic intravesical therapy. Mitomycin and Gemcitabine are the most commonly used drugs in intravesical chemotherapy. Valrubicin is another chemotherapy drug used in some cases. The side effects of intravesical chemotherapy include irritation and a burning sensation in the bladder. The significant advantage of giving the drug directly to the bladder is that the drug will not affect other systems and parts of the body. Hence, the common side effects of chemotherapy can be avoided.
Conclusion
Intravesical therapy is an effective treatment in the early stages of cancer, where the cancer cells are limited to the lining of the bladder. The advantage of the therapy is that the drug does not affect the other body parts.
