The Immune System and Cancer
- (Photo courtesy of MIT)
- Overview
The immune system is important to people with cancer because: cancer can weaken the immune system; cancer treatments might weaken the immune system; the immune system may help to fight cancer.
Some cells of the immune system can recognize cancer cells as abnormal and kill them. But this may not be enough to get rid of a cancer altogether. Some treatments aim to use the immune system to fight cancer.
Cancer and treatments can weaken immunity. Cancer can weaken the immune system by spreading to the bone marrow. The bone marrow produces blood cells that help fight infection. This most commonly occurs in leukemia or lymphoma, but can also occur in other cancers. Cancer can stop the bone marrow from making so many blood cells.
Certain cancer treatments temporarily weaken the immune system. This is because they cause the number of white blood cells produced in the bone marrow to drop. Cancer treatments that are more likely to weaken the immune system include: chemotherapy, targeted cancer drugs, radiation therapy, and high-dose steroids.
- Roles of the Immune System in Cancer
The immune system normally identifies and destroys abnormal cells, including cancer cells, but cancer cells can evade this surveillance. Immunotherapies work by boosting the immune system's ability to recognize and attack cancer cells, essentially enhancing the body's own defense mechanisms to fight cancer.
1. The Immune System's Role in Fighting Cancer:
- Surveillance: The immune system, a complex network of cells, tissues, and organs, is designed to protect the body from foreign invaders like bacteria and viruses, as well as abnormal cells.
- Targeting Cancer Cells: Specialized immune cells, such as T cells, can recognize cancer cells as "foreign" or abnormal and attempt to destroy them.
- Ongoing Battle: Cancer develops from the body's own cells, and an ongoing "war" exists between the immune system's attempts to control cancer and the cancer's efforts to grow and spread.
2. How Cancer Evades the Immune System:
- Hiding: Cancer cells can develop mechanisms to avoid detection by the immune system.
- Immune Suppression: Cancer cells can have proteins on their surface that interfere with the immune response, effectively turning off the immune attack.
- Immune Microenvironment: The environment around the tumor can also become suppressive, preventing immune cells from effectively attacking the cancer.
3. Immunotherapy: Using the Immune System Against Cancer:
- Boosting Immunity: Immunotherapy is a type of cancer treatment that uses a patient's own immune system to fight cancer more effectively.
- Marking Cancer Cells: Some immunotherapies work by marking cancer cells for destruction or by removing the "checkpoints" that prevent T cells from attacking the tumor.
- Types of Immunotherapy: Different forms of immunotherapy, such as non-specific immune stimulation and immune checkpoint inhibitors, work to enhance the immune system's anti-cancer capabilities.
- Cancer and Treatments
The immune system is crucial for cancer patients because cancer and its treatments can weaken it, increasing the risk of infection. Conversely, the immune system plays a vital role in fighting cancer by recognizing and killing cancer cells, a process that can be bolstered by immunotherapy.
However, cancer cells can evade immune detection, and treatments like chemotherapy, radiation, and high-dose steroids can temporarily suppress the immune system, creating a complex interplay between the body's defenses and the disease.
1. How Cancer and Treatments Weaken the Immune System:
- Cancer's impact: Cancer can spread to the bone marrow, where blood cells that fight infection are produced, leading to a decrease in these protective cells, according to Cancer Research UK.
- Treatment side effects: Many cancer treatments, such as chemotherapy, radiation, and high-dose steroids, temporarily weaken the immune system by reducing the number of white blood cells the bone marrow produces.
2. The Immune System's Role in Fighting Cancer:
- Natural immune response: The immune system, particularly its white blood cells, can recognize cancer cells as abnormal and destroy them.
- Immunotherapy: This is a type of cancer treatment that works by stimulating or modifying the body's own immune system to better detect and fight cancer cells.
- Immune evasion: Despite these efforts, cancer cells can develop ways to hide from or interfere with the immune system, making it harder for the immune system to eliminate the cancer entirely.
3. The Goal of Immunotherapy:
- Strengthening the immune response: Immunotherapies aim to help the immune system recognize cancer cells and attack them more effectively, acting as a "re-education" or "boost" for the body's defenses, notes Cancer Research UK.
- Overcoming cancer's defenses: Immunotherapies are designed to work around the defenses cancer cells use to avoid detection and destruction by the immune system, according to the National Cancer Institute.
[More to come ...]
