Neutropenia is a condition that develops when a person does not have enough neutrophils, which are a type of white blood cell. It is a common side effect of chemotherapy.

Most cases of chemotherapy-induced neutropenia resolve on their own once chemotherapy stops, so they do not require treatment.

However, neutropenia can make someone vulnerable to serious infections, and it may delay cancer treatment while a person waits for their neutrophil levels to rise.

This article will explore chemotherapy-induced neutropenia, why it occurs, and which drugs have the strongest links to the condition. Read on to learn about the diagnosis, treatment, and management of neutropenia.

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Neutropenia refers to a low amount of neutrophils. Neutrophils are infection-fighting white blood cells. They are an important part of the immune system.

Neutropenia is a common side effect of chemotherapy treatment. When this happens, doctors call it chemotherapy-induced neutropenia.

There are usually no symptoms, although some people may feel tired. Most people learn they have the condition when doctors take a blood test during chemotherapy.

A low number of neutrophils means the body is more vulnerable to infectious diseases. The longer neutropenia lasts and the lower the neutrophil count, the higher a person’s risk of developing an infection.

Chemotherapy involves taking drugs that destroy cancerous cells. However, they can also damage healthy cells, including blood-forming stem cells. These are cells that have the potential to become red or white blood cells or platelets.

A lack of blood-forming cells means a person cannot produce as many neutrophils. If chemotherapy destroys neutrophils faster than the body can make them, it may result in neutropenia.

Some chemotherapy drugs are more likely to cause neutropenia than others. The following chemotherapy drugs are known to have a higher risk of neutropenia:

  • alkylating agents
  • antimetabolites
  • anthracyclines (doxorubicin or daunorubicin)
  • taxanes (paclitaxel or docetaxel)
  • epipodophyllotoxins
  • hydroxyurea (Hydrea)
  • mitomycin C
  • vinblastine

In 2021, researchers analyzed a number of chemotherapy drugs and the risk factors that might make someone more predisposed to neutropenia during cancer treatment. They found the condition was more likely in people who were undergoing chemotherapy and:

  • were over 65 years old
  • had a low body mass
  • were female

During chemotherapy, a cancer team will monitor a person’s absolute neutrophil count (ANC) as a standard protocol. This is so they can get an idea of how well the immune system is coping during chemotherapy.

To do this, doctors use a simple blood test known as a complete blood count. This measures the white blood cells to determine the ANC.

A cancer care team will also monitor the person for signs and symptoms of neutropenia, although many people having chemotherapy do not show obvious symptoms.

This is because symptoms are a sign of the body fighting off an infection. However, with neutropenia, the body has too few neutrophils to do this effectively.

If symptoms do show up, they may include one or more of the following:

  • fever
  • chills
  • sores in the mouth
  • cough
  • difficulty breathing
  • abdominal pain
  • rectal pain

The treatment for chemotherapy-induced neutropenia is usually watchful waiting. Doctors will wait for the neutrophil count to return to healthier levels.

In some cases, a doctor may prescribe white blood cell growth factors, or colony-stimulating factors (CSFs). This treatment can help the body produce more white blood cells. Doctors usually give CSFs as a shot after chemotherapy.

However, doctors do not routinely offer CSFs to everyone, as they are not suitable for all people. They can also cause unpleasant side effects, such as bone pain, fever, and a feeling of being unwell.

If neutropenia goes on for longer than anticipated, a doctor may recommend a person take antibiotics to reduce the risk of infections.

Neutrophil counts drop around a week after each round of chemotherapy, reaching their lowest point at around 7–14 days. This is the period in which the risk of infection is at its highest.

After this, the body begins to produce more neutrophils again. However, it may take 3–4 weeks for blood counts to be healthy enough to have more chemotherapy.

Doctors may delay the next round of chemotherapy if neutrophil levels do not return to normal quickly enough. Alternatively, they may lower the dose of chemotherapy in the next round of treatment.

The Centers for Disease Prevention and Control (CDC) recommends that people with neutropenia take certain precautions to reduce the risk of infection. These include:

  • practicing good hygiene by washing hands, showering regularly, and asking others to do the same
  • avoiding sexual intercourse or using condoms and water-based lubricants during sex
  • cooking meat and eggs thoroughly to kill any germs
  • washing fruit and vegetables thoroughly before eating
  • isolating from people who may have an infection, such as a cold
  • avoiding people who have recently been vaccinated
  • avoiding crowded places
  • not sharing cutlery, dishes, cups, or personal items with others
  • using gloves while gardening
  • using a soft toothbrush to brush the teeth
  • keeping household surfaces clean
  • getting the seasonal flu shot

Some experts advise that people who have neutropenia should also avoid certain foods to reduce the risk of being exposed to microbes and bacteria that may cause an infection.

However, a 2019 systematic review and meta-analysis found there was no evidence to support recommending a specific diet or restricting certain foods. Instead, the authors advise people to simply follow safe food handling guidelines.

Neutropenia develops when a person does not have enough neutrophils, which are a type of white blood cell. Chemotherapy-induced neutropenia is a common result of cancer treatment. In most cases, though, it is temporary and improves on its own with time.

While someone has neutropenia, they are at an increased risk for infections. Doctors may recommend antibiotics to protect a person from bacterial infections. Practicing good hygiene and food safety can also help to reduce the risk of infection.