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Why Does Cancer Make You Immunocompromised?
People with cancer might get infections more easily because cancer and its treatments can weaken the immune system. Your immune system helps your body fight germs.
What does it mean to be immunocompromised?
Being immunocompromised means you have a weak immune system. You might have a harder time than a healthy person fighting off infections from viruses, bacteria, or other germs.
What can make you immunocompromised?
Some types of cancer and cancer treatments lower your white blood cell counts. When you have too few of certain white blood cells, called neutrophils, it is called neutropenia. This makes it easier to get an infection.
Other things that can make you immunocompromised include:
Other diseases or infections
- HIV/AIDS
- Diabetes
- Heart or lung problems
- Autoimmune diseases
- Sores in your mouth or throat
Medical treatments or devices
- A central line, tube, or drain in your body
- A long hospital stay
- A bone marrow or stem cell transplant
- An organ transplant
- Other medicines that weaken your immune system, such as steroids
Lifestyle factors
- Not getting enough sleep
- Not eating well
Ask your cancer care team if you are at a higher risk for infection.
What cancer types weaken your immune system?
Some types of cancer weaken your immune system and raise the risk of infection more than others.
Blood cancers tend to raise the risk the most. These include cancers that start in the bone marrow, which makes immune cells that fight germs. Cancers that can crowd out or damage the bone marrow include leukemia, lymphoma, and multiple myeloma.
Tumors that press on or break through body tissue can also raise your risk of infection by letting in germs or blocking normal body passages. For example, a tumor blocking the airway can lead to pneumonia, and blocked urine or bile tubes can lead to infection.
How long does cancer treatment weaken your immune system?
Some cancer treatments weaken the immune system for a short time. Others can weaken it for a long time. The extent depends on the type of treatment and on your health.
The most common cancer treatments that can increase your risk for infection include:
- Surgery
- Chemotherapy
- Radiation therapy
- Immunotherapy
- Targeted drug therapy
- Bone marrow or stem cell transplant
Some newer immunotherapies, such as CAR T-cell therapy and bispecific antibodies, can weaken your immune system for months. This can raise the risk of infection even after treatment ends.
Nutrition and infection risk in people with cancer
Cancer and its treatment can make it harder to get the nutrients your body needs.
- The cancer itself can make it hard to eat or digest food. This is common with cancers of the digestive system, mouth, or throat.
- Cancer treatments can make you less hungry. For example, treatments such as chemotherapy and radiation can cause nausea. This can lead to a condition called cancer-related anorexia.
- The cancer can change how your body uses food. It can cause weight and muscle loss, even if you try to eat more. This is called cachexia. Eating more does not always fix it.
Poor nutrition is also called malnutrition. It can make the immune system weak. A weak immune system has a harder time fighting germs.
- Written by
- References
Developed by the American Cancer Society medical and editorial content team with medical review and contribution by the American Society of Clinical Oncology (ASCO).
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Hosseini SM, Salari N, Darvishi N, et al. Prevalence of severe malnutrition in cancer patients: A systematic review and meta-analysis. J Health Popul Nutr. 2025; 44(1):230.
Jatoi A, Loprinzi C. Pathogenesis, clinical features, and assessment of cancer cachexia. UpToDate. 2026. Accessed at https://www.uptodate.com/contents/pathogenesis-clinical-features-and-assessment-of-cancer-cachexia on October 6, 2026.
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National Comprehensive Cancer Network (NCCN). Anemia and neutropenia: Low red and white blood cell counts. NCCN Guidelines for Patients. Updated 2021. Accessed at www.nccn.org on October 6, 2026.
National Comprehensive Cancer Network (NCCN). Prevention and treatment of cancer-related infections. Version 1.2023. NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines). Updated June 2023. Accessed at www.nccn.org on October 6, 2026.
Rozga M, Moloney L, Handu D. Dietitian-provided interventions for adults with cancer: an umbrella review of systematic reviews. Nutr Cancer. 2025;77(6):575-589.
Wingard JR. Prophylaxis of infection during chemotherapy-induced neutropenia in high-risk adults. UpToDate. 2026. Accessed at https://www.uptodate.com/contents/prophylaxis-of-infection-during-chemotherapy-induced-neutropenia-in-high-risk-adults on October 6, 2026.
Last Revised: November 9, 2026
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