What High Neutrophils May Mean for People with Cancer

High neutrophils can happen for several reasons during cancer care. Learn what neutrophils do, common causes of high levels, and when doctors may monitor them more closely.

What are neutrophils?

Neutrophils are a type of white blood cell. They help the body fight infections caused by bacteria and fungi.

Doctors often check neutrophil levels during a complete blood count (CBC). A CBC measures white blood cells, red blood cells, and platelets. A high neutrophil count is called neutrophilia.

Common causes of high neutrophils

High neutrophils usually mean the body is responding to stress, inflammation, or infection. Inflammation is the body’s response to injury or irritation. Common causes include:

• Infection
• Physical stress from illness or surgery
• Inflammation
• Steroid medicines
• Some cancer treatments
• Smoking
• Emotional stress
• Certain blood cancers

Doctors usually review symptoms, medical history, and other lab results before deciding what the high count may mean.

Cancer treatments may raise neutrophils

Some cancer treatments can increase neutrophil levels. Steroid medicines like dexamethasone may cause neutrophils to move into the bloodstream.

Growth factor treatments can also raise neutrophils. These medicines help the bone marrow make more white blood cells after cancer treatment. Examples include filgrastim (Neupogen, Amgen) and pegfilgrastim (Neulasta, Amgen). Higher neutrophils after these treatments are often expected. 

This may help lower infection risk during chemotherapy. Doctors still monitor blood counts closely during treatment.

Infections can increase neutrophils

Bacterial infections are one of the most common causes of high neutrophils.

People with cancer may have a weaker immune system from treatment. Because of this, doctors monitor possible infections carefully. Signs of infection may include:

• Fever
• Chills
• Cough
• Pain
• Redness or swelling
• Shortness of breath

Doctors may order more tests if high neutrophils happen along with infection symptoms.

Some blood cancers affect neutrophil counts

Certain blood cancers may directly increase neutrophils. Examples include:

• Chronic myeloid leukemia (CML)
• Chronic neutrophilic leukemia (CNL)
• Some myeloproliferative neoplasms (MPNs)
• Some cases of acute myeloid leukemia (AML)

Doctors may look at the full blood count pattern along with bone marrow or genetic testing.

High neutrophils alone do not diagnose cancer. Many non-cancer conditions can also raise neutrophil levels.

When doctors may monitor high neutrophils more closely

Doctors may watch neutrophil levels more carefully if:

• Counts stay high over time
• Levels rise quickly
• Other blood counts are abnormal
• Symptoms are present
• Infection is suspected

More testing may include repeat blood tests or infection testing. Regular blood monitoring helps doctors understand how treatment and the immune system are responding.

Questions to ask your doctor

If your neutrophils are high, you may want to ask:

• What may be causing my high neutrophil count?
• Could my treatment affect these results?
• Do I need more testing?
• Should I watch for infection symptoms?
• How do my other blood counts look?

High neutrophils are common during cancer care. Infection, inflammation, medicines, and some blood cancers can all affect neutrophil levels. Your care team will review your symptoms, treatment, and blood count trends to understand what the results may mean for you.

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Sources: 

• Neutrophils in cancer: from immune defense to tumor promotion
• Neutrophils in cancer carcinogenesis and metastasis
• The role of neutrophils in cancer
• Neutrophilia
• Neutrophils in Cancer and Potential Therapeutic Strategies Using Neutrophil-Derived Exosomes
• Neutrophils in Cancer: Two Sides of the Same Coin