Breast cancer treatment is commonly associated with chemotherapy. But when you yourself are faced with a breast cancer diagnosis, knowing the ins and outs of chemotherapy can be confusing and overwhelming.

Here’s what you need to know about chemotherapy for HER2-positive breast cancer.

What Is Chemotherapy?

Chemotherapy, or chemo, is the use of medicines to kill cancer cells and stop new ones from growing. Cancer cells multiply very quickly, so chemotherapy drugs target cells in the body that grow and divide very quickly.

Other cells in the body, including those in the bone marrow, the lining of the mouth and gut, and the hair follicles, also grow and divide quickly. These cells may also be affected by the chemotherapy drugs and may trigger side effects.

Some chemotherapy drugs can be taken by mouth, but most are given intravenously through an injection into a vein. You will have to go to a clinic or hospital to receive intravenous (IV) chemotherapy medications.

You and your oncology team will decide whether chemotherapy is right for you. If you decide to use chemotherapy, your oncology team may prescribe a combination of anticancer drugs. This treatment regimen may include a few different chemotherapy drugs as well as specialized medications that target HER2-positive breast cancers.

Everyone’s breast cancer is a little bit different. The number and type of medications your oncology team prescribes will depend on your treatment goals and the characteristics of your particular cancer.

Chemotherapy Side Effects

Side effects depend on the types and doses of chemotherapy drugs prescribed by your oncology team. Common chemotherapy side effects include:

  • hair loss
  • nausea and vomiting
  • fatigue or extreme tiredness
  • loss of appetite
  • bleeding or bruising
  • anemia (low red blood cell count)
  • low white blood cell count
  • rash
  • numbness and/or tingling in fingers or toes
  • taste changes

Chemotherapy can destroy red blood cells. These are the cells that help carry oxygen to all the different tissues and organs in your body. If your red blood cell count is low, you might be told that you have anemia. Symptoms of anemia often include:

  • fast heart beat
  • shortness of breath
  • trouble breathing when doing everyday activities like walking, talking, or climbing stairs
  • dizziness
  • chest pain
  • pale skin, nail beds, mouth, and gums
  • extreme tiredness or fatigue

These side effects usually go away after chemotherapy treatment is finished. If you have any of these side effects, tell your oncology team. There are often ways to lessen the side effects at your next treatment.

Chemotherapy can also destroy white blood cells, the cells that help fight infection. Neutrophils are the most abundant type of white blood cells and are very important in preventing you from getting sick. If the neutrophil count in your blood is too low, you could be at risk for an infection.

Your oncology team will monitor your white blood cell count, paying close attention to your neutrophil count, and they will prescribe additional treatments if needed to keep your white blood cells from dropping too low. There are no symptoms of a low white blood cell count, but if you develop an infection you may notice a fever. If you have a fever alert your oncology team immediately.

When Will I Start Chemotherapy?

In general, chemotherapy or HER2-targeted therapies are more likely to be given prior to surgery.

You’ll receive the chemotherapy in cycles, with each period of treatment followed by a period of rest to let your body recover.

Chemotherapy begins on the first day of the cycle. Cycles can last anywhere from about two to four weeks depending on the chemotherapy drug or combination of drugs.

With some drugs, chemotherapy is given on the first day of the cycle only. Other drugs may be given weekly, while others may be given daily for a period of time.

Chemotherapy generally lasts between about three to six months. The total length of chemotherapy treatments may vary depending on the stage of breast cancer, including how far it has spread in the body, as well as a number of other factors.

Additional Therapies

HER2-positive breast cancer means that the cancer cells make too much HER2, which can cause tumors to grow more aggressively than with other forms of breast cancer.

Luckily, there are special medications that target HER2. Your oncology team may refer to these medications as targeted therapy or HER2-directed therapy. Trastuzumab (Herceptin) and pertuzumab (Perjeta) are probably the most commonly used drugs, but there are others, such as lapatinib (Tykerb/Tyverb) or ado-trastuzumab emtansine (Kadcyla), that target HER2-positive breast cancer cells too.

HER2-directed therapy is often given at the same time as chemotherapy through an IV. HER2-directed therapy usually lasts longer than chemotherapy. You may get doses of these medications for a year or longer.

If you have HER2-positive breast cancer, talk to your oncology team about chemotherapy and your treatment schedule.