Neulasta in Breast Cancer Chemotherapy and Side Effects

Neulasta being given during breast cancer chemotherapy
Neulasta is administered via an injection. BSIP/UIG/Getty Images

Neulasta (pegfilgrastim) is a medication sometimes used during breast cancer chemotherapy to increase white blood cell counts in order to reduce the risk of infections. What do you need to know about this drug, including the possible side effects?

Neulasta (Pegfilgrastim) Overview

Neulasta (pegfilgrastim) is a drug given to people who have or are expected to develop chemotherapy-induced neutropenia (a low neutrophil count, one type of white blood cell) during breast cancer chemotherapy. Neulasta is a synthetic version of a granulocyte colony-stimulating factor (G-CSF), a compound which stimulates the production of white blood cells in the bone marrow. It is a clear liquid that is usually given as a shot in which the needle is inserted just under the skin.

Neulasta is a long-acting drug which is usually needed only once following a chemotherapy infusion, in contrast to Neupogen (filgrastim), which is give daily for several days by injection.

Use For Breast Cancer

Chemotherapy for breast cancer affects all the rapidly dividing cells in your body, including bone marrow cells, which produce white blood cells, red blood cells, and platelets. This bone marrow suppression during chemotherapy can result in anemia (a low red blood cell count), neutropenia (a low neutrophil count) and thrombocytopenia (a low platelet count.)

A low neutrophil count (sometimes simply called a low white blood cell count) can be serious in that it can predispose people receiving chemotherapy to infections. The goal of using Neulasta is to help prevent these infections.

How Neulasta Works

Usually, your body produces a protein that stimulates the production of neutrophils. During chemotherapy, your body's own production of neutrophils is interrupted, Neulasta functions to stimulate production of neutrophils, and to mature and activate neutrophils already present.

How Neulasta is Given

You will get an injection of Neulasta about 24 hours after your chemotherapy infusion. It may not be given sooner because it may be less effective. Unlike Neupogen, which must be given repeatedly until your neutrophil counts rise, Neulasta is given just once per a 2- or 3-week chemotherapy cycle. You can have this injection in your upper arm, abdomen, thigh, or buttocks.

Some oncologists have patients give themselves their own injection the day following chemotherapy, and an automatic "on body injection" is also available. Other oncologists recommend that you have the injection at your clinic or with your primary care doctor in case of allergic reactions to the drug.

Alternatives to Neulasta

As noted earlier, an alternative to Neulasta (pegfilgristim) is Neuopogen (filgristim). Sometimes an oncologist will ask which medication you prefer. Athough the drugs work in the same way, there are somedifferences between Neulasta and Neupogen as well, including the frequency of injections, the tolerability, and the cost.

Some Common Side Effects

One of the more serious side effects from Neulasta is an allergic reaction, and again, this is the reason that some oncologists prefer you have the shot done at a clinic. If you do give yourself your shots at home, you should be familiar with the symptoms of a possible allergic reaction or anaphylaxis.

A fever may occur, and it is important for your doctor to determine if your fever is due to your injection, or rather an infection related to your lowered white blood cell count.

Nearly a third of people given Neulasta injections mention some type of bone pain. Earlier studies found that Naprosyn/Aleve (naproxen) reduced both bone pain and sleep disturbances (presumably due to bone pain). Recently it was found that the antihistamine Claritin (loratidine) both decreased the risk of adverse effects and resulted in fewer people stopping the medication than those treated with Aleve/Naprosyn (naproxen). If you do note bone pain, talk to your doctor about what medication she recommends you use. Soaking in a warm bath can also help with bone pain from Neulasta.

Call Your Doctor if You Have These Symptoms

Less common side effects and adverse reactions may occur, and it's important to call your oncologist if you have any symptoms which concern you. This is especially important if you note:

  • Unusual fatigue and lethargy
  • Chest pain
  • Heart palpitations

Urgent Symptoms Include

You should call your doctor right away, but seek immediate medical attention (call 911) if you notice any symptoms suggestive of an anaphylactic reaction (severe allergic reaction) such as:

  • Hives
  • Difficulty breathing
  • Swelling of your face, lips, tongue, or throat
  • A rash spreading over your body
  • Abdominal pain, especially pain in your left upper abdomen
  • Severe shoulder pain

Possible Risks of Using Neulasta

Neulasta is a relatively safe drug used for many types of neutropenia, and the majority of the time, the side effects or risk of the medication outweigh the risk of a low neutrophil count. Adverse reactions which are uncommon (but sometimes occur) include:

  • Serious allergic reactions.
  • Adult respiratory distress syndrome (ARDS).
  • Sickle cell crisis in people with sickle cell anemia.
  • Splenic rupture.
  • Potential for stimulating tumor growth (this is a theoretical possibility and has not been demonstrated, as Neulasta is a growth factor)

Who Should Avoid This Drug

Do not take this drug if:

  • You are pregnant or breastfeeding
  • You are allergic to Neulasta
  • You are allergic to products made using the bacteria E. coli

Recommendations During Treatment

Before your first injection of Neulasta, your doctor will order regular CBC's (complete blood counts) to see the levels of your platelets and red and white blood cells, with special attention to the absolute number of neutrophils in your blood. As treatment progresses, you will have more blood tests to check the effectiveness of Neulasta.

If you are nursing or pregnant, discuss this with your doctor before taking Neulasta. There have not been enough studies done to determine the effect of this drug on breast milk or the human fetus.

Reducing Your Risk of Infections During Chemotherapy

Even if you are receiving injections of Neulasta to raise your white blood cell count, you may still be at risk of developing an infection during chemotherapy. Sometimes white blood cells, even if there are enough, do not function as well. And even with using Neulasta, you may have times after your infusion when your white blood cell count falls below the levels at which infections are more likely to occur. Take a moment to learn about what you can do yourself to reduce your risk of an infection during chemotherapy. Hint: some of these measures are not well known and may surprise you.

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