Absolute Neutrophil Count (ANC) for Cancer Treatment

Neutrophils are the most important type of white blood cell (WBC) for fighting infection. An absolute neutrophil count (ANC) is a test that assesses how many neutrophils are in your bloodstream.

Your neutrophil counts may be lower than normal for a number of reasons. Diseases and medical treatments can both cause a low count. For example, a drop in ANC can happen during cancer chemotherapy.

This article looks at the absolute neutrophil count test, its interpretation, and some of the causes of low ANC.

What Is an ANC Test?

A healthy person has an absolute neutrophil count of between 1,500 and 6,000. Your ANC can be found with a common blood test called the complete blood count (CBC). The CBC gives your doctor your numbers for:

• Red blood cells, which carry oxygen and carbon dioxide to and from your tissues
• White blood cells (WBCs), which help your body fight infection
• Platelets, the small bits of cellular material that help control bleeding

The ANC is found by multiplying the total white blood cell count by the percent that are neutrophils.

Modern blood counting tools can automatically find the number of each type of white blood cell and report the ANC. Lab professionals can also find the number using a microscope. This may be done to confirm findings or give more details.

Lab results may also include "bands" and "segs." Bands are immature neutrophils, while segs are mature. These numbers are added together to get the total.

Interpreting ANC Results

It’s possible to have a normal total WBC count but a low neutrophil count. Usually, though, the WBC count is low when the neutrophil count is low. This is because neutrophils are normally the most abundant white blood cells. In most healthy people, they make up more than 50% of the white blood cell count.

Neutropenia occurs when you have abnormally small numbers of neutrophils in your blood. The degree of neutropenia you have depends on how low your ANC goes.

A healthy person has an ANC between 2,500 and 6,000. When the ANC drops below 1,000, there may be an increased risk of infection. When this happens, your doctor will want to closely monitor your counts. You are at a much greater risk of infection when your ANC is below 500.

If your ANC is low or your healthcare providers expect it to drop, they may give you antibiotics to help prevent infection. You may also be given growth factor. This medicine helps boost your neutrophil production.

What Causes Low ANC?

Neutrophils and other blood cells are made in your bone marrow. Life-saving cancer therapies like chemotherapy and radiation may target rapidly growing cells. Because this can impact the production of neutrophils, a drop in ANC can be an expected side effect. A low ANC can also be a sign of the disease itself, as in some types of blood cancer.

Low ANC may also happen during treatment for other illnesses. These include autoimmune disorders like rheumatoid arthritis. When you have an autoimmune disorder, your immune system mistakes a normal part of your body for an invader.

One of the treatments for rheumatoid arthritis is tocilizumab. This drug works by blocking a signal that causes inflammation in the body. It has been linked to lower ANCs, though this doesn't seem to be associated with serious infections.

It is possible to have severe chronic primary neutropenia. This is low ANC that occurs with no known cause. The condition is rare but happens more often in females. Despite low ANC, though, severe infections are uncommon. The condition isn't well understood, but patients usually have an overall favorable outcome.

Low ANC Symptoms

You won't necessarily have noticeable symptoms just because your WBC count or ANC is low. That's why it's important to watch for signs of infection. Unfortunately, as your ANC gets lower, these signs may not be as obvious.

Here are some things to look out for:

• Fever
• Chills
• Cough
• Trouble breathing
• Diarrhea
• Pain

If you have a central venous access device, also called a central line or port, check for signs of infection. Look for redness, swelling, pain, or pus where the tube enters your body. A person with a low ANC might not have redness or pus, but could still have an infection.

If your ANC is 1,000 or lower and you have a fever, your doctor may assume there is an infection. When this happens, you'll likely be given antibiotics right away, before the source of the infection is found.

Your medical team will then try to narrow down the likeliest cause from a list of possible pathogens. When they find the site and cause of the infection, they can choose a treatment that targets the specific germ. This means you may be switched to a different antibiotic.

Summary

Neutrophils are a type of white blood cell that help your body fight infection. An ANC test measures the number of neutrophils in your blood. 

Your neutrophils might be low because of a disease or the treatment for a disease like cancer or an autoimmune disorder. Some patients have low ANC with no known cause, though this is rare.

In most healthy people, more than 50% of white blood cells are neutrophils. When your ANC is low, you may need to be monitored closely for signs of infection.