Hormone Therapy for Breast Cancer
When a woman (or, on occasion, a man) is diagnosed with breast cancer, one of the things her doctor needs to determine before deciding on a course of treatment is the cancer's hormone receptor status. A hormone is a chemical released by a cell or a gland in one part of the body that sends out signals that affect cells in other parts of the body. Hormone receptors are cell proteins that pick up the hormone signals. Hormone receptors for the female hormones estrogen and progesterone can signal the cancer cells to grow even faster.Breast cancer is classified as either hormone receptor positive or hormone receptor negative. A cancer is called estrogen-receptor-positive (ER+) if it has receptors for estrogen. The cancer is progesterone-receptor-positive (PR+) if it has progesterone receptors. According to www.breastcancer.org:
- · About 80% of breast cancers are estrogen-receptor positive.
- · About 65% of estrogen-receptor-positive breast cancers are also progesterone-receptor-positive.
- · About 13% of breast cancers are estrogen-receptor-positive and progesterone-receptor-negative.
- · About 2% of breast cancers are estrogen-receptor-negative and progesterone-receptor-positive.
In patients with hormone receptor cell positive cancer, hormone therapy is given to block the body's naturally occurring hormones and fight the cancer's growth. Hormonal therapy medicines treat hormone-receptor-positive breast cancers in two ways:
- 1. They lower the amount of the hormones estrogen or progesterone in the body, and
- 2. They block the production of hormones by the body (e.g. by shutting down the ovaries).
Hormone therapy for breast cancer (also called hormonal therapy or hormone treatment) not to be confused with the hormone replacement therapy (HRT) used to treat the symptoms of a hormonal imbalance in menopause. HRT treats menopausal symptoms by boosting the amount of hormones in the body, while hormone therapy for breast cancer reduces or blocks hormones.
Breast cancer hormone therapy should also not be confused with chemotherapy, or chemo. Chemotherapy medicines are usually given in a combination called a chemotherapy regimen. There are several chemotherapy regimens to effectively treat different stages of breast cancer. Chemotherapy is not commonly used for small non-invasive cancers, but is recommended for premenopausal women, for women whose cancer has spread to the lymph nodes, and for women with more aggressive forms of cancer.
Also, hormone receptors should not be confused with HER2 receptors. HER2 (human epidermal growth factor receptor 2) is a gene that plays a role in the development of about one-quarter of breast cancers. The HER2 gene makes breast cell receptors called HER2 proteins. In HER2 positive breast cancer, the gene malfunctions and spurs uncontrolled cell growth. HER2 positive cancers are more aggressive and more likely to recur than other cancers.
Hormonal therapy medications are not effective against hormone-receptor-negative breast cancers. Hormone therapy drugs commonly used to fight hormone receptor positive breast cancer include:
1) Aromatase inhibitors:
- · Arimidex (generic anastrozole)
- · Aromasin (generic exemestane)
- · Femara (generic letrozole)
2) SERMs (Selective Estrogen Receptor Modulators):
- · tamoxifen
- · Evista (generic raloxifene)
- · Fareston (generic toremifene)
3) ERDs (Estrogen Receptor Downregulators):
- · Faslodex (generic fulvestrant)
Most oncologists now believe that aromatase inhibitors are the best choice of hormone therapy for early stage hormone positive breast cancer, after studies showed it to be more effective than the commonly prescribed tamoxifen.
Side effects of aromatase inhibitors tend to be less that those with tamoxifen. The most common aromatase inhibitors side effects involve joint stiffness and/or pain. Less frequently, women have experienced bone loss. Interestingly, a British study found that the women who experienced the most aches and pains had the least incidence of breast cancer recurrence
