Neutropenia

Neutropenia is a condition caused by lower-than-normal amounts of neutrophils, a type of white blood cell. Neutrophils fight infection by killing harmful bacteria in the blood. Chemotherapy can cause neutropenia because it kills rapidly dividing cells, including cancer cells and healthy white blood cells. Other cancer treatments can also cause neutropenia.

Neutropenia can put you at a higher risk of infection, which is one of the most serious complications of chemotherapy. On this page, we'll talk about symptoms and causes of neutropenia, and ways to reduce your risk or manage it if it does happen.

What are the symptoms of neutropenia?

Neutropenia doesn’t always cause symptoms you can see or feel. You may first learn you have neutropenia in the results of blood tests that you get before each chemotherapy treatment. These tests check on important features of your blood, including your white blood cell (WBC) count. Your WBC count shows the amount of infection-fighting neutrophils in your blood. A normal neutrophil count, also known as the Absolute Neutrophil Count, or ANC, is between 2,500 and 5,000. A low neutrophil count of less than 1,000 signals neutropenia.

If you have noticeable symptoms that could mean infection, they may include:

• Fever
• Pain when you urinate
• New lower back pain
• Stuffed nose
• Shaking chills
• Redness, swelling, pain, or warmth of the skin, at the site of an injury, or around a central line catheter or port
• Diarrhea or change in the odor of your stool
• Breathlessness or cough
• Unusual vaginal itching or discharge
• Sore throat

Talk with your care team about when to call them to report fever or other symptoms. If you develop neutropenia with fever (febrile neutropenia) and infection, this is an emergency and considered life-threatening. Even a minor infection can quickly become serious. Seek immediate help from your doctor if you develop a fever or you have any other signs of infection.

What causes neutropenia?

The most common cause of neutropenia during cancer treatment is chemotherapy, though other types of cancer medicine can also cause it. Chemotherapy targets cells that divide quickly, such as cancer cells. It can also affect other quickly dividing cells in our bodies, including white blood cells, red blood cells, and platelets. When chemotherapy destroys too many white blood cells, neutropenia occurs.

Not everyone who has chemotherapy develops neutropenia, and the symptoms and how severe they are can vary among those who do. The same is true if it’s caused by other types of cancer treatments, so talk with your care team about your treatment plan and the risk of neutropenia.

Other cancer treatments that may cause neutropenia include:

• Radiation therapy
• Some targeted therapies:
  • Olaparib (Lynparza)
  • Talazoparib (Talzenna)
  • Ado-trastuzumab emtansine (Kadcyla)
  • Pertuzumab (Perjeta)
  • Trastuzumab (Herceptin)

Causes not related to cancer include:

• Exposure to other medicines or chemicals
• Autoimmune diseases
• Bone marrow disorders
• Vitamin deficiencies, such as B12, folate, or copper
• A virus
• Alcoholism
• Other diseases caused by infection or a parasite

How can I reduce my risk of developing neutropenia?

Neutropenia is hard to prevent because cancer medicines such as chemotherapy can’t tell the difference between cancer cells and neutrophils. One way your doctors might try to prevent neutropenia is with medicines called growth factors, which increase blood counts. Growth factors are given as injections under the skin, and are more likely to be used if you’re getting a chemotherapy medicine with a high risk of causing neutropenia.

If you develop neutropenia, your doctors may prescribe an antibiotic to lower your risk of getting an infection.

How can I manage neutropenia?

Neutrophil counts usually start to go down about a week after each round of chemotherapy. They reach their lowest point about 7 to 14 days after your treatment day. You’re most likely to get an infection during that time.

Your doctor may prescribe a growth factor to help raise your white blood cell counts and prevent neutropenia. Growth factors include filgrastim (Neupogen) or pegfilgrastim (Neulasta), or their generic versions, filgrastim-sndz (Zarxio) and pegfilgrastim-jmdb (Fulphila).

Some medicines, such as filgrastim, are made of living cells, which makes it impossible to create an exact generic version. But labs can create medicines that are so similar to them that they have the same treatment results. These kinds of generic medicines are called biosimilars. Biosimilars are designed to work as well and be as safe as the original medicine, but may be significantly less expensive.

Sometimes growth factors are not enough to get your white blood cell counts back up. If white blood counts stay very low between chemotherapy cycles, your doctor may adjust your treatment dose or schedule.

If you have neutropenia, here are some steps you can take to help reduce your risk of an infection:

• Wash your hands often! Keep your hands clean and encourage those who come into contact with you to do the same. This is your best line of defense.
• Brush your teeth regularly.
• Avoid contact with people who have colds, the flu, COVID-19, or people who live with a person who was recently sick.
• Clean any cuts and cover them with a bandage.
• Avoid raw foods, including:
  • Fruits with thin peels (such as grapes, peaches, nectarines)
  • Uncooked vegetables
  • Undercooked meat, fish, and eggs
  • Unpasteurized milk, yogurt, cheese, and dairy products
  • Well water
• Avoid large crowds where there is a greater chance of contacting germs, such as shopping malls, houses of worship, or other large gatherings.
• Avoid swimming or wading in hot tubs, ponds, lakes, and rivers.

Sometimes, neutropenia requires a hospital stay. If you develop a fever and blood tests show low ANC, your care team may recommend admitting you to the hospital for care. During your stay, you will be given intravenous (IV) antibiotics and tests to check for infection. If you develop a fever but blood tests show normal ANC levels, or you have slightly lower ANC levels but no fever, you may not need to be hospitalized. But because you can only know your ANC levels by having a blood test, it's very important to let your care team know right away if you develop a fever. Untreated infections with neutropenia are life threatening.

If you do develop neutropenia, your neutrophil level should go back to normal between 3 and 4 weeks after treatment ends.

Neutropenia and metastatic breast cancer treatment

Metastatic breast cancer (MBC) treatments can also cause neutropenia. Continuous treatment increases the risk of cumulative effects on the bone marrow, and this can increase the risk for neutropenia.

If you develop neutropenia, the ongoing nature of metastatic breast cancer treatment does put you at higher risk of developing a serious infection. And while rare, neutropenia can also happen if breast cancer that has traveled to the bones, called bone metastasis, becomes very advanced. If the cancer is in bones that have a lot of bone marrow, such as the pelvis or femur, it can crowd out healthy bone marrow cells. And because bone marrow is an important source of white blood cells, crowding out marrow cells can cause neutropenia.

If a treatment you’re given has a high risk of causing neutropenia, your doctor may prescribe a growth factor to lower that risk. Growth factors can also be given to increase blood counts once they’ve already dropped.

Treatments approved for metastatic breast cancer that can cause neutropenia include:

• Chemotherapy
• Some targeted therapies:
  • Abemaciclib (Verzenio)
  • Palbociclib (Ibrance)
  • Ribociclib (Kisqali)
  • Sacituzumab govetican (Trodelvy)

Ongoing treatment and bone metastases can also put you at higher risk of febrile neutropenia (neutropenia with fever), which usually requires a hospital stay. Once you’ve had febrile neutropenia, you’re at higher risk of developing it again in the future.

If you develop neutropenia, there are things your care team can do, such as:

• Lower the dose of your medicine
• Allow more time in between treatments
• Give you a treatment break, a temporary pause to allow your blood counts to increase
• Switch you to a new treatment