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About Breast Cancer > Treatment > Hormonal Therapy

Hormonal therapy for breast cancer

What is hormonal therapy?
Hormonal therapy has played an important role in all stages of the treatment and prevention strategy for breast cancer. Breast cancers all develop from abnormal breast cells which are often sensitive to sex hormones, such as oestrogens and progesterone. By depriving cancer tumours of these hormones the growth stimulus is removed.

Hormonal therapy acts on hormone receptors of the cancer cells. It works by decreasing the production of hormones in the body or by blocking the body’s natural hormones from reaching breast cancer cells. Hormonal therapy is used after surgery, chemotherapy, or radiotherapy.

What are hormonal receptors?
Hormones are produced by the organs and cells of the body. Oestrogen is the main female sex hormone produced by the ovaries before menopause. It is present at low levels after menopause when it is then produced by the adrenal glands.

Hormonal receptors are proteins on the surface of a cell and are able to bind to hormones. If oestrogen is present, it will attach to oestrogen receptors on breast cancer cells, possibly making the tumour grow larger. Breast cancer cells which have hormonal receptors on their surface are considered to be hormonal receptor positive. There are two types of hormonal receptor – oestrogen receptors and progesterone receptors. Hormonal therapy may be suitable for women with either type of receptor on their breast cancer cells.

Are all breast cancer patients suitable for hormonal therapy?
To assess if a patient is suitable for hormonal therapy, hormone sensitivity of the tumour or its receptor status has to be determined by testing of the breast specimen removed at biopsy or surgery.

Tumours expressing significant levels of receptor proteins are described as oestrogen receptor positive (ER +ve) and / or progesterone receptor positive (PR +ve).

Tumours not expressing significant levels of these receptor proteins are described as receptor negative (ER -ve / or PR -ve) and are unlikely to respond to hormonal therapy.

According to the Breast Cancer Facts in Hong Kong 2008 Report, 77 % of breast cancer cases are ER+ve and 62% are PR +ve. Fifty eight per cent of the patients received hormonal therapy.

Types of hormonal therapies
The different therapies available to reduce the level of female hormones include:

  1. anti-oestrogens
  2. aromatase inhibitors
  3. anti-ovarian treatments.

Anti-oestrogen drugs slow down breast cancer growth by attaching to oestrogen receptors on the breast cancer cells. The result is that the activity of oestrogen is blocked and so it cannot stimulate the growth of breast cancer tumours. The most common anti-oestrogen is Tamoxifen. It is used in both pre-menopausal and post-menopausal women. Tamoxifen is taken as a single daily tablet, usually for 5 years. Tamoxifen not only treats cancer, but also helps reduce the risk of osteoporosis and lower the cholesterol level.

Aromatase inhibitors
In post-menopausal women, the primary source of oestrogen is the conversion of androgen. The adrenal gland produces androgens and the enzyme aromatase changes them into oestrogens, which can cause breast cancer cells to grow. Aromatase inhibitors block the enzyme aromatase and thus prevent the conversion of androgens into oestrogen. This decreases the level of oestrogen and the blinding of oestrogen receptors. Finally, it stops the growth of cancer cells.

Aromatase inhibitors are only effective for women who have gone through menopause permanently. Aromatase inhibitors included Anastrozole (Arimidex), Letrozole (Femara) and Exemestane (Aromasin). They are taken as a single daily tablet, usually for 5 years.

Recent studies have shown further reduction in risk of recurrence and risk of cancer in the opposite breast, together with improvement in overall survival by adding aromotase inhibitors after 5 years of Tamozifen treatment in post menopausal women. This means receiving hormonal therapy for 7.5 years or beyond.

Anti-ovarian treatments
Anti-ovarian treatments work by stopping the ovaries from producing oestrogen. Drugs like Goserelin (Zoladex) stop the ovaries from producing oestrogen temporarily when the drug is taken. A permanent method of stopping oestrogen production in women is to remove the ovaries or administer radiotherapy to the ovaries. Anti-ovarian treatments are only suitable for women who have not yet reached menopause.

Common side effects of hormonal therapies
Hormonal therapies have common side effects and different women may respond differently to the same treatment.

  • All hormonal therapies can cause menopausal symptoms such as hot flushes and vaginal dryness.
  • All hormonal therapies can reduce the libido (sex drive).
  • The severity of these symptoms varies between women and the different treatments available. The effects often improve when the treatment stops.

Side effects of anti-oestrogen (Tamoxifen )

  • Increased risk of deep vein thrombosis, pulmonary embolism and stroke.
  • Thickening of the uterine lining and cancer of the uterus can develop.

Side effects of aromatase inhibitors

  • Aromatase inhibitors can cause joint pain or stiffness.
  • Also, an increase in the risk of fractures resulting from speeding up of the normal thinning of bones (osteoporosis).

Side effects of anti-ovarian treatments

  • Removal of the ovaries by surgery or radiotherapy to the ovaries causes permanent menopause.
  • Women who have had these treatments can no longer have children. Drugs that stop the ovaries from functioning also cause menopause, but this is usually temporary, lasting only as long as the drugs are continued. However, the effects of these drugs may be permanent in women who were close to having their natural menopause when they started treatment.
Nursing tips:
  • Treatment with hormonal therapies can sometimes result in permanent menopause. If you have not yet reached menopause and are still considering having children, it is important to discuss your options with your doctor before starting treatment.
  • Regular gynaecological check ups are important while you are taking hormonal therapy.
  • Consult your doctor immediately for any new or unusual symptoms, in particular irregular vaginal bleeding, chest pain or warmth, swelling, pain or tenderness in limbs.
  • If you are already at increased risk of osteoporosis, discuss with your doctor for recommendations on the most suitable hormonal therapy for you.
  • Healthy eating: Eat plenty of fresh vegetables, fruits, cereals (including breads, rice, pasta and noodles). Select foods which are low in fats, particularly meat which should be lean meat. Try to take reduced-fat dairy products and use low-fat cooking methods. Drink at least eight glasses of water daily. Ensure you receive enough vitamin D from sunlight and foods such as eggs, salmon and sardines.
  • Perform regular physical exercise: Being active is highly advisable. Aim for 30 minutes of moderate physical activity daily to maintain general health, control weight and to help keep bones healthy.
  • Avoid smoking and drinking.
  • Look after your emotional health: You may experience mood changes such as depressed moods and irritability. These are often related to physical changes like hot flushes, night sweats and interrupted sleep. Talk to your doctor or breast care nurse about techniques for controlling physical symptoms and improving emotional health.
  • Relaxation: Try to do relaxing activities such as having regular massages, listening to relaxing music and meditation.
  • Join a support group for mutual support.

Special thanks to Dr. Diana Siu for editing

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