Lung cancer treatments can sometimes lead to other conditions that affect your health. One of these conditions affects your neutrophils, which are white blood cells (WBCs) that help fight infections. When levels of neutrophils in the blood drop too low, it is called neutropenia.

Neutrophils are a specific type of white blood cell that fights infections. Neutropenia occurs when neutrophil counts drop below 1,500 neutrophils per microliter of blood. If the count drops below 1,000 neutrophils, it is considered dangerous and may require treatment.

Febrile neutropenia is diagnosed if a person has low neutrophil levels along with a fever. A related condition, leukopenia, occurs when the total number of white blood cells is low. Leukopenia may mean that a person has low levels of neutrophils or a different type of WBC.

One study looking at non-small cell lung cancer (NSCLC) found that about 1 out of 4 people developed mild neutropenia in response to chemotherapy. Another 1 out of 4 people developed severe neutropenia, which is defined as having 500 neutrophils per microliter of blood or less. Neutropenia can also occur in people undergoing chemo for small cell lung cancer (SCLC) or any other type of cancer.

Other types of white blood cells include lymphocytes, monocytes, basophils, and eosinophils. Cancer and cancer treatments can affect the levels of these cells, causing trouble for the immune system. Here’s what you should know about neutropenia and other white blood cell abnormalities.

What Causes Neutropenia?

Lung cancer itself doesn’t affect neutrophil levels. Instead, neutropenia develops as a side effect of lung cancer treatments.

Chemotherapy and radiation therapy can cause neutropenia. These treatments kill cancer cells, but they can also kill the body’s healthy cells. In particular, chemotherapy and radiation treatments affect cells that come from stem cells located in the bone marrow (the soft tissue found inside certain bones).

Stem cells are responsible for making all of the body’s blood cells. During lung cancer treatments, blood stem cells often become damaged and have a harder time making new neutrophils. This causes neutrophil levels to drop.

Although neutropenia is a serious risk factor for infections, having severe neutropenia from chemotherapy is usually linked to better outcomes because it means that chemotherapy is working. People with NSCLC and neutropenia caused by chemotherapy have slightly better survival rates.

Other Causes of Neutropenia

Neutropenia is most often caused by chemotherapy. However, other factors can affect white blood cell storage and production.

Other possible causes of neutropenia include:

• Vitamin or mineral deficiencies, including a lack of folate, vitamin B12, or copper
• Other medications, including antibiotics, antiviral drugs, thyroid medications, anti-inflammatory medications, or antipsychotic drugs
• Infections such as hepatitis, sepsis, Lyme disease, or chickenpox
• Autoimmune disorders like lupus, Crohn’s disease, or rheumatoid arthritis
• Blood cancer or blood disorders, including aplastic anemia, myeloproliferative neoplasms, or myelodysplastic syndrome

Symptoms of Neutropenia

Neutropenia does not often directly cause symptoms. In some cases, infections that the body cannot fight off cause symptoms like fever, tiredness, or swelling.

One significant effect of neutropenia is that it makes fighting off infections more difficult. When there aren’t enough neutrophils in the body to fight off germs, infections can quickly become life-threatening. Immediately notify your health care team or go to the emergency room if you are undergoing lung cancer treatments and you notice signs of infection. Prompt antibiotic treatment can help protect you against infections.

Symptoms of an infection may include:

• A fever of at least 100.5 degrees Fahrenheit (38 degrees Celsius)
• Chills or sweating
• Coughing or breathing problems
• Extreme tiredness
• Abdominal pain
• Vomiting
• Pain while urinating
• Pain near the anus
• Diarrhea
• Vaginal discharge
• Swelling or discoloration under the skin
• Mouth sores
• Forgetfulness or confusion

Many members of MyLungCancerTeam have reported dealing with infections. These conditions are sometimes severe and can lead to pain and discomfort.

“The pain that I was having was due to another infection in my lung,” wrote one member.

Another said, “My husband keeps getting infections and has hardly eaten a thing in almost two months.”

One member reported needing hospitalization. “I was in the emergency room on Monday with a massive sinus infection,” they shared. “Immunotherapy focuses my immune system on fighting cancer while leaving my immune system suppressed in fighting bacteria, virus, and fungal infections.”

Treatments for Neutropenia

In some cases, low neutrophil levels may not need any treatment. However, treatment may be necessary when neutrophil levels drop very low or when a person with neutropenia also develops a fever or infection.

Neutropenia treatments often involve growth factors, also called granulocyte colony-stimulating factors. These drugs trigger the stem cells to start making more blood cells.

Growth factor drugs include:

• Filgrastim (Neupogen)
• Pegfilgrastim (Neulasta)
• Tbo-filgrastim (Granix)

If you develop an infection as a result of neutropenia, it will need to be treated right away. Doctors prescribe drugs like antibiotics to help treat infections.

Many drugs can treat or prevent neutropenia and infections. They are given subcutaneously (under the skin), occasionally intravenously (through a vein), or with an on-skin injector that you take home.

In 2021, the U.S. Food and Drug Administration (FDA) approved a medication that works differently — trilaciclib (Cosela) — to help treat neutropenia. This drug helps prevent stem cells from becoming damaged by oncology (cancer) drugs, allowing them to continue making more of the body’s normal blood cells. Trilaciclib is approved for people with advanced SCLC.

Read more about specific medications in this list of treatments for lung cancer.

How Does Neutropenia Affect Lung Cancer Treatments?

If you already have low neutrophil levels, receiving cancer treatments that can lead to a further drop in neutrophil levels can be risky. People with neutropenia often have to wait for their neutrophil levels to rise before undergoing treatments.

Several MyLungCancerTeam members have had to put treatments on hold because of low white blood cell counts. “Well, my day did not actually go as I had planned!” said one member. “Did my blood work for my chemo treatment on Monday, but apparently my white blood cell count is too low. So, they will have to do my blood test again Monday morning to see if it is up enough so I can have my chemo treatment.”

Tips for Avoiding Infections With Neutropenia

People with neutropenia have an increased risk of developing serious infections. Make sure to keep yourself safe with these tips:

• Wash your hands often. When soap and water aren’t available, use hand sanitizer.
• Avoid large crowds, wear a mask, and practice social distancing.
• Stay home if you feel unwell.
• Avoid meeting up with friends or family members who are feeling sick or might have infections.
• Cook meat thoroughly.
• Wash fruits and vegetables before you eat them.
• Practice good oral hygiene, including brushing your teeth and flossing.
• Clean and bandage any cuts or scratches.
• Stay up to date on vaccinations.

Lymphocytopenia Is Similar to Neutropenia

Lymphocytopenia, or lymphopenia, is a condition similar to neutropenia. About 20 percent to 40 percent of white blood cells are lymphocytes. A healthy range of lymphocytes for adults is 1,000 to 4,800 per microliter of blood. When levels drop below 1,000, it’s called lymphopenia.

Lymphopenia may be caused by cancer or cancer treatments. Just like neutropenia, it weakens the immune system.

When Your White Blood Cell Counts Are High

Leukocytosis is the state when your white blood cell counts are too high. Since half of white blood cells are neutrophils, neutrophilia (elevated neutrophil levels) is the most common type of leukocytosis.

Leukocytosis can be a response to any type of inflammation, including cancer. Your health care team will monitor your white blood cell counts throughout your cancer treatment to watch for any dangerous fluctuations.

Talk With Others Who Understand

MyLungCancerTeam is the social network for people with lung cancer. On MyLungCancerTeam, more than 12,000 members come together to ask questions, give advice, and share their stories with others who understand life with lung cancer.

Have you experienced neutropenia following lung cancer treatments? What steps do you take to protect against the high risk of infection? Share your experience in the comments below, or start a conversation by posting on your Activities page.