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Understanding Immunotherapy
Many people, after being diagnosed with cancer, worry about the subsequent treatment process, especially the side effects that may arise from the treatments. Generally, there are three main methods for treating cancer: radiotherapy (commonly known as radiation therapy), chemotherapy (often abbreviated as chemo), and surgical operations. However, these treatment methods may damage normal tissues outside of cancer cells, leading to various side effects such as vomiting, diarrhea, hair loss, and even impacting sexual function.
In fact, in addition to the aforementioned three treatment methods, some patients have the option to undergo immunotherapy. Immunotherapy refers to the use of the patient’s immune system to inhibit or slow the growth of tumors and prevent their spread to other parts of the body. Overall, compared to radiotherapy and chemotherapy, the side effects of immunotherapy are relatively milder.
What is Immunotherapy？
Principle
The human immune system attacks foreign “intruders,” such as bacteria, to maintain health. Usually, cancer cells that suddenly grow in the body should also be a target for the immune system’s attack. However, this is not always the case. Some cancer cells can emit signals that allow them to hide from the immune system or even prevent it from functioning correctly. A type of drug known as “immune checkpoint inhibitors” targets this characteristic by intercepting the signals emitted by cancer cells that suppress the immune system, making it easier for the immune system to identify cancer cells. Additionally, patients can receive drugs to stimulate their immune system or have samples of their immune system extracted, trained in the laboratory to attack cancer cells, and then reintroduced into the patient’s body to assist the immune system in actively eliminating cancer cells.
7 Main Types of Treatments
Therapies
Immunotherapy mainly includes the following types:
- Adoptive Immunotherapy
Doctors extract T cell samples [Note 1] from the patient’s blood, proliferate them in large quantities in the laboratory, and reintroduce them into the patient’s body to help their immune system kill cancer cells. T cells may be modified in the laboratory to target and attack cancer cells more effectively.
- Angiogenesis Inhibitors
Suppose a tumour is to grow beyond a few millimeters. In that case, it will first emit signals to stimulate the formation of new blood vessels, which supply oxygen and nutrients through the blood to enable the tumour to expand and invade nearby tissues. Unlike most immunotherapy methods, this approach does not directly inhibit the tumour’s growth but blocks the blood vessels that assist tumour growth.
- Bacillus Calmette-Guérin (BCG) Therapy
This is the most common immunotherapy for early-stage bladder cancer, inhibiting the growth of cancer cells and preventing cancer recurrence. Doctors introduce BCG into the patient’s bladder via a catheter, attracting the immune system to the bladder to start killing cancer cells there. After receiving BCG therapy, patients may experience symptoms such as fever, fatigue, and bladder pain and may have frequent urination or blood in the urine.
- Chimeric Antigen Receptor (CAR) T-Cell Therapy
T cells are first extracted from the patient’s blood. Cancer cells contain a specific protein, and doctors combine this protein with the gene for a chimeric antigen receptor and the T cells extracted from the patient’s blood, then inject the mixture back into the patient’s body.
- Cytokine Therapy
This controls the immune response to produce appropriate immune effector cells to eliminate tumours. It is usually conducted after the patient has completed radiotherapy, chemotherapy, or surgical operations.
- Immune Conjugate Therapy
Immune substances such as “monoclonal antibodies” [Note 2] are linked to substances that can kill cells, including toxins and radioactive isotopes [Note 3]. The former identifies specific cells in the body, including cancer cells, while the latter kills those cells without harming others.
- Oncolytic Virus Therapy
Doctors introduce a virus into the patient’s body. Once the virus infects the tumour, it replicates itself until the cancer cells burst. The cancer cells release residual substances, such as tumour antigens, making them easier for the immune system to identify.
Doctors will select the appropriate immunotherapy method based on the patient’s cancer type, size, extent, and physical condition. However, most of the above therapies are only available in clinical trials at medical clinics. Patients should consult their doctors for advice before deciding to undergo immunotherapy.
Note 2: Monoclonal antibodies are antibodies produced by a single type of immune cell.
Note 3: Isotopes are variants of the same chemical element with the same number of protons but different numbers of neutrons.
American Cancer Society
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