Immune System

What the Immune System Is

The immune system is your body’s natural defense system. It is made up of many parts, including white blood cells, organs like the thymus and spleen, lymph nodes, and bone marrow. These parts work together to protect you from infections caused by germs such as bacteria and viruses, as well as from harmful changes in your own cells, like cancer. Your skin and mucous membranes also help keep germs out as the first line of defense.

Why the Immune System Matters in Cancer Care

The immune system plays an important role in cancer. It can sometimes recognize and attack cancer cells, helping to control or slow cancer growth. However, cancer or its treatments, like chemotherapy, can weaken the immune system. A weakened immune system makes it harder for your body to fight infections and may increase the risk of certain cancers. Some cancer treatments, called immunotherapy, work by boosting the immune system’s ability to fight cancer.

Signs of a Weakened Immune System

People with weakened immune systems may not always have clear symptoms, but they are more likely to get infections that last longer or are more severe. For example, infections like shingles or cryptosporidiosis (a parasite causing diarrhea) are more common and serious in people with weakened immunity. If you have watery diarrhea lasting several days or unusual infections, especially during cancer treatment, it is important to contact your healthcare provider.

Where You Might Hear About the Immune System

The term “immune system” may come up in your medical records, treatment plans, or when discussing side effects of cancer treatments. Your care team might explain how treatments like chemotherapy can lower your immune defenses or how immunotherapy aims to strengthen them. You may also hear about immune system health when discussing risks for infections or vaccines, such as the shingles vaccine, which is recommended for people with weakened immunity.

Common Questions to Ask Your Care Team

It’s helpful to ask how your immune system might be affected by your cancer or treatment, what signs of infection to watch for, and what steps you can take to protect yourself. You can also ask about vaccines, infection prevention, and whether immunotherapy might be an option for your care.

Understanding the Term in Context

When you see “immune system” mentioned, it does not always mean your immunity is weak or that you have an infection. It often refers to how your body naturally fights disease or how treatments might affect that ability. It’s important to discuss with your healthcare provider what it means for your specific situation.

Important Safety Note

This information is meant to help you understand the immune system in general and in relation to cancer. It does not replace medical advice. Always talk with your healthcare team about your own health, symptoms, and treatment options.

Next Steps

If you have questions about your immune system, infections, or cancer treatments, bring them up at your next visit. Knowing how your immune system works and how it may be affected can help you take better care of your health during and after cancer treatment.