How breast cancer treatments can affect the immune system

In In The News by Barbara Jacoby


Treatment for breast cancer is highly effective. Five-year survival rates for breast cancer have increased dramatically in recent decades, and much of that success can be credited to cancer researchers and campaigns designed to inform women about the importance of screenings.

Breast cancer is highly treatable, but treatment typically leads to some unwanted side effects. According to Johns Hopkins Medicine, women undergoing treatment for breast cancer may experience a host of side effects, including fatigue, pain, headaches, and dental issues. Cancer treatments, most notably chemotherapy, also can take a toll on women’s immune systems.

Why does chemotherapy affect the immune system?

Cancer is caused by an uncontrolled division of abnormal cells in the body. According to, chemotherapy targets these abnormal cells, but also can affect fast-growing cells that are healthy and normal. So chemotherapy can damage cells throughout the body, including those in bone marrow. When bone marrow is damaged, it’s less capable of producing sufficient red blood cells, white blood cells and platelets. notes that the body is more vulnerable to infection when it does not have enough white blood cells.

Does chemotherapy always weaken the immune system?

The effects of chemotherapy on the immune system depend on various factors. According to, a patient’s age and overall health may influence the effects of chemotherapy on their immune systems. Young, healthy patients may be less vulnerable to infections from weakened immune systems than aging, less healthy patients. However, Susan G. Komen notes that the median age for breast cancer diagnosis in the United States is 63, so many patients are likely to be affected by the impact that treatment can have on their immune systems. The length of treatment and amount of medicines patients receive also can affect the impact of chemotherapy on patients’ immune systems. notes that being administered two or more chemotherapy medicines at once is more likely to affect the immune system than just one medication.

Other treatments

Chemotherapy is not the only treatment that can affect breast cancer patients’ immune systems. The Cancer Treatment Centers of America notes that surgery, radiation, CAR T-cell therapy, stem cell transplants, and even immunotherapy can affect the immune system. Surgery can overtax the immune system and compromise its ability to prevent infections and heal wounds caused by the procedure. Like chemotherapy, radiation therapy can damage healthy cells and lead to an increased risk of infection. And while immunotherapy is designed to boost the immune system by helping it recognize and attack cells more effectively, it also can lead to an overactive immune system that attacks healthy cells.

Cancer treatment is often highly effective. However, patients may need to work with their physicians to combat treatment side effects that can adversely affect their immune systems.