Metastasis is the name given to the process of spread of cancer. Like any other cancer, breast cancer also spreads to other parts of your body. Breast cancer has several methods of spreading, including direct spread, lymphatic spread, bloodstream spread, and spread via the pleural or peritoneal cavity. The lymphatic spread is the commonest.
Systemic therapy aims to delay or prevent the metastatic spread of cancer.
Systemic therapy includes:
Chemotherapy uses drugs that are toxic to cancer cells and kills the cancer cells. This is usually used after surgery to kill any remaining cancer cells that have not been removed. This is called adjuvant chemotherapy. This is most beneficial to premenopausal women.
There are several regimens used for chemotherapy. Three medications are commonly given at once. One of the first regimens used is CMF containing Cyclophosphamide, Methotrexate and 5-Fluorouracil. This has been used for many years and is now largely replaced by cyclophosphamides and an anthracycline. The choice of the medications given to you will depend on the type of breast cancer you have and it’s spread. These regimens of chemotherapy help to increase the survival rate up to 30%.
You do not have to stay overnight to receive chemotherapy, therefore, it is usually done as an outpatient procedure. The chemotherapy drugs will be directly administered to your blood via a drip. In some cases, these drugs are given orally and can be taken at home. You may have repeated sessions of chemotherapy once every two to three weeks.
Even though chemotherapy drugs are designed to attack cancer cells, they sometimes attack the normal healthy cells as well, thus producing side effects.
These side effects include:
- Loss of hair
- Nausea and vomiting
- Loss of appetite
- Frequent infections due to immune suppression caused by the drugs
- Induced early menopause. If you have not yet reached menopause, your periods may stop during the chemotherapy. However, your periods should start once chemotherapy is stopped.
Some cancers are due to hormones, such as estrogen and progesterone, that are produced in your body. These types of cancers are known as hormone receptor positive cancers. Hormonal therapy works by reducing the level of these hormones and stopping their effect.
Hormonal therapy is usually started after surgery and you may have to continue them for about five years or more.
The type of hormonal therapy you receive will depend on many factors, such as stage and grade of the tumor you have and if you have reached menopause or not.
There are three types of hormonal therapies that are being used. These include ovarian ablation, Tamoxifen, and Aromatase Inhibitors.
Estrogen is produced from your ovaries. In ovarian ablations a drug called goserelin, which is a luteinizing hormone-releasing hormone analogue (LHRH analogue), is given that will permanently stop the ovaries from working and stop estrogen production. Your periods will stop once you start taking this drug. Ovarian ablations can also be achieved by an oophorectomy, a surgical procedure of removing ovaries.
Tamoxifen is a selective estrogen receptor blocker (SERM) that blocks the estrogen from binding to its receptors in the breast. It is given as a tablet or a liquid to be taken every day.
Tamoxifen has several side effects which include:
- Post-menopausal symptoms such as vaginal dryness and hot flushes.
- Visual disturbances
- Increased risk of thromboembolism
- Increased risk of endometrial carcinoma
Aromatase Inhibitors (AIs)
Aromatase is an enzyme that converts androgens in the peripheral adipose tissue to estrogen. Aromatase inhibitors will inhibit this enzyme and will prevent the production of estrogen. This drug will be given only if you have reached menopause because before menopause occurs, estrogen is synthesized by your ovaries, not in the peripheral tissues.
Some breast cancers are stimulated by a protein called as the human epidermal growth factor receptor 2 (HER2). These cancers are called HER2 positive cancers. Biological therapy targets on these cancers and stops the effects caused by these receptors. If you have high levels of HER2 receptors, you will be prescribed a drug called Trastuzumab or Herceptin, a monoclonal antibody against the HER2 receptor.