Chemotherapy is a type of systemic treatment (treating the whole body) in which drugs are used to kill cancer cells. Chemotherapy medications may be used in combination or as a single agent (called monotherapy).1 In metastatic breast cancer, sequential single agents are usually recommended. This method uses one chemotherapy drug at a time, one after another, and the drug is changed to another when the breast cancer no longer responds or begins growing, or when the patient can no longer tolerate the specific drug.2
An individual may be prescribed chemotherapy at different points in their treatment process, and it may be used with the attempt of eliminating or controlling the breast cancer. Chemotherapy medications may potentially be given in an injection, tablet/capsule form, or as an intravenous (IV) infusion, and the frequency and dosage are dependent on the individual and the medications chosen.1,3
When chemotherapy is used to treat breast cancer
Chemotherapy may be used as an adjuvant (after primary therapy) treatment in early breast cancers to reduce the risk of recurrence. Chemotherapy may also be used before surgery in certain cases to reduce the size of a tumor. In advanced or metastatic breast cancer, chemotherapy may be the primary treatment, and it may be used in combination with certain targeted therapies.1,2
How chemotherapy works
Cancer occurs when there are mutations to the DNA of the cell that cause it to grow and reproduce uncontrollably. While all cells divide, cancer cells divide at a rapid pace and do not stop dividing as healthy cells do. Chemotherapy drugs work by targeting rapidly dividing cells and damaging the DNA or RNA to stop the cells from growing. Unfortunately, chemotherapy can also damage healthy cells that divide rapidly, such as hair cells and cells that line the digestive tract. When these healthy cells are damaged by chemotherapy, side effects can occur.1,3
Types of chemotherapy used in advanced breast cancer
The choice of chemotherapy agents is an individualized process and is dependent on several factors, including the patient’s treatment history, their general health, and the benefits and toxicities of each chemotherapy drug.4 There are several different types of chemotherapy, which work in different ways to stop cancer cells, including:
Taxanes, such as Taxol® (paclitaxel), Taxotere® (docetaxel), Abraxane® (albumin-bound paclitaxel)
Anthracyclines, such as Adriamycin® (doxorubicin), Doxil® (pegylated liposomal doxorubicin), Ellence™ (epirubicin)
Platinum agents, such as Platinol® (cisplatin), Paraplatin® (carboplatin)
Other chemotherapy drugs that may be used in the treatment of breast cancer include:
Neosar®, Cytoxan® (cyclophosphamide)
5-FU, Adrucil® (fluorouracil)
Common side effects of chemotherapy
Each chemotherapy drug is unique and has different possible side effects. Not all drugs cause the side effects below, and not everyone on a particular treatment experiences the same side effects. Common side effects of chemotherapy include:
Decreased blood cell counts, which can increase the risk of infection, bleeding, and/or anemia
This is not an exhaustive list of all possible side effects. Patients should talk to their doctor about their specific chemotherapy drugs and what side effects they might experience.
Managing side effects of chemotherapy
Some side effects from chemotherapy can be prevented, and many can be managed. Reducing the dosage, changing medications, or delaying treatment regimens can be potential options to help manage certain side effects. Communication between patients and their healthcare team is key, and any side effects a patient experiences should be brought to the attention of a doctor or nurse.
Chemotherapy for breast cancer. American Cancer Society. Available at https://www.cancer.org/cancer/breast-cancer/treatment/chemotherapy-for-breast-cancer.html. Accessed 10/4/18.
Chemotherapy for metastatic breast cancer in 2017. OncLive. Available at https://www.onclive.com/insights-archive/bc-targeting-angiogenesis/chemotherapy-for-metastatic-breast-cancer-in-2017. Accessed 10/4/18.
Chemotherapy: the basics. OncoLink. Available at https://www.oncolink.org/cancer-treatment/chemotherapy/overview/chemotherapy-the-basics. Accessed 10/4/18.
O’Shaughnessy J. Extending survival with chemotherapy in metastatic breast cancer. The Oncologist. 2005 Oct;10(3):20-29. doi: 10.1634/theoncologist.10-90003-20.