Chemotherapy and Breast Cancer

Chemotherapy is the administration of cytotoxic drugs to destroy cancer cells. There are more than 50 types available, used alone or in combination, either intravenously or orally. Cytotoxic drugs are usually given in cycles, interspersed with one- to three-week breaks to allow patients to recover from side effects.

Chemotherapy is given to breast cancer patients with a higher risk of recurrence and those with advanced breast cancer with a high risk of propagation. It may also be used to treat a recurrence of breast cancer or to relieve pain or control the symptoms of advanced breast cancer (palliative chemotherapy).

Chemotherapy aims to slow or prevent cancer cells from multiplying or spreading in the body. There are two strategies for this type of treatment:

  • Neoadjuvant chemotherapy is used to decrease the size of a large breast tumour before surgery.
  • Adjuvant chemotherapy aims to remove remaining cancer cells after surgery and to reduce the risk of developing new cancer.

Because chemotherapy is a systemic treatment that destroys growing cells, it also affects healthy cells and thus can cause the following side effects:

  • Lower blood cell counts
  • Infection
  • Nausea and vomiting
  • Diarrhea or constipation
  • Fatigue
  • Weight and hair loss
  • Loss of appetite
  • Pain in the mouth and sore throat
  • Early menopause
  • Fertility disorders
  • Cognitive disorders and damage to the nervous system

You may be given medications to help manage side effects (antinausea drugs, antibiotics to reduce the risk of infection, colony stimulating factors to prevent blood cell depletion).

The doctor’s decision to administer chemotherapy depends on the patient’s risk of recurrence. It is offered to those at high risk of recurrence because it significantly reduces this risk. For those at medium risk, doctors discuss the decision with patients to assess the risks and side effects of chemotherapy. Low-risk patients do not receive chemotherapy because it will not reduce their risk of recurrence. The goal is to avoid chemotherapy when it is not expected to provide benefits, as it can be difficult to tolerate. Research (notably studies on genetic analysis and biomarkers) is ongoing to determine who actually benefits from chemotherapy.

Infographic on the process of chemotherapy with breast cancer.
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