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Changes in Hormone Levels

The purpose of hormonotherapy is to slow down the growth and spread of the diseased cells in certain cases of breast cancer, by modifying in the patient’s body the level of hormones linked to the disease, namely estrogen and progesterone.

These two hormones are produced mainly by the woman’s ovaries until menopause. After menopause the body continues to produce a small quantity of these hormones through an enzyme called aromatase. There are in fact, on the surface of some breast tumours, areas called receptors to which estrogen and progesterone can bind.

These tumours, which are said to be hormone receptor positive, are the ones treated with hormonotherapy. Hormonotherapy reduces the estrogen and progesterone level in the body or blocks the effect of these hormones on the cancerous cells. By establishing the hormone receptor status we can determine the presence of either estrogen or progesterone receptors, or of both.

Here are the main methods of reducing the level of these hormones through hormonotherapy:

  • anti-estrogen drugs, also called selective estrogen receptor modulators or SERMs, block estrogen receptors by binding directly to them, thus preventing the cancer cells from obtaining estrogen. Tamoxifen (Nolvadex, Tamofen), that is available in pill form, is the most frequently used anti-estrogen drug. As for fulvestrant (Faslodex), it reduces the number of estrogen receptors on breast cancer cells. It is injected into the muscle of the buttocks;
  • aromatase inhibitors, an enzyme that contributes to the body’s production of estrogen. These inhibitors are also medication. However they stop the production or block the action of aromatase. They are prescribed only to menopausal women;
  • surgery to remove the ovaries (ovariectomy or oophorectomy), which are the main source of estrogen in premenopausal women. Here we mean, of course, women who do not want to have any or any more children.

Hormonotherapy is often prescribed after surgery, radiotherapy and chemotherapy to prevent relapses of breast cancer. However, certain health problems such as osteoporosis or a high risk of the formation of blood clots, as well as having already been treated with hormonotherapy, can prevent a woman with breast cancer from getting this treatment again.

Side Effects of Hormonotherapy

Hormonotherapy can cause side effects that vary depending on the type of medication or the treatment regimen used. Among the possible effects are the appearance of symptoms of menopause (hot flashes or vaginal dryness), weight gain, early menopause, loss of libido as well as joint or muscle pain. For many women, these side effects are minor and disappear with time, but for others they persist for a long time or may even be permanent.