Find out how hormone therapy for breast cancer works, and which types are available based on age and menopausal status. Learn how it can reduce the risk of cancer recurrence.
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Overview
Hormone therapy, also called endocrine therapy or hormone-blocking therapy, slows or stops the effect of oestrogen. It’s used to treat breast cancer that is hormone receptor positive.
It’s often used to lower the risk of the cancer coming back. It may also be used to reduce the risk of certain conditions, including some non-invasive breast conditions, developing into invasive breast cancer.
There are different types of hormone therapy. The type used will depend on your age, type of breast cancer and if you have reached menopause.
Tamoxifen
Tamoxifen can be used at any age, whether you have been through menopause or not. You need to take a daily tablet for 5–10 years.
Side effects
In females, tamoxifen can cause menopausal symptoms like hot flushes and mood changes, although it doesn’t bring on menopause. It may also cause changes in thinking and memory, and vaginal discharge. There is a very small risk of developing cancer of the uterus (endometrial cancer) if you have gone through menopause. Let your doctors know if you have any unusual vaginal bleeding. In males, side effects can include low sex drive (libido) and erection problems
Tamoxifen increases the risk of blood clots. See a doctor immediately if you have swelling, soreness or warmth in an arm or leg, or a sudden shortness of breath or chest pain.
You are unlikely to have all of these side effects, and they usually improve with time. Your doctor and breast care nurse can help you to manage side effects.
Tell your doctor if you take an antidepressant. Some types of antidepressant drugs may affect how well tamoxifen works.
Aromatase inhibitors
After menopause, the ovaries stop making oestrogen. However, both females and males make small amounts of oestrogen in body fat and the adrenal glands. Taking aromatase inhibitors will help reduce the amount of oestrogen in the body. This is important because oestrogen can cause some cancers to grow.
Aromatase inhibitors are mostly used if you have been through menopause, have had your ovaries removed or are male. They may also be used if you have not been through menopause but there is a high risk of the cancer coming back.
If you have not gone through menopause, you may be advised to take an extra treatment to stop the ovaries from making oestrogen.
Side effects
Aromatase inhibitors can cause menopausal symptoms such as vaginal dryness and low mood. These drugs may also cause itchiness, joint pain and stiffness, and weakening of the bones (osteoporosis). Your bone health will be monitored during treatment and you may be prescribed a drug to protect your bones.
You should consider seeing a physiotherapist or exercise physiologist for an exercise plan. If you have arthritis, aromatase inhibitors may worsen joint stiffness and pain. Exercise or medicines from your doctor may help. Your doctor may also suggest changing to another type of aromatase inhibitor.
Ovarian suppression
If you have not been through menopause, drugs or surgery can stop the ovaries from producing oestrogen. This is called ovarian suppression.
It may also be recommended as an additional treatment for people taking tamoxifen or for premenopausal women taking an aromatase inhibitor instead of tamoxifen.
Temporary ovarian suppression
A drug that stops the ovaries from producing oestrogen is given by injection. Side effects are similar to those of permanent menopause. The drug may also help protect the ovaries during chemotherapy, so it’s often given to women who want to preserve their fertility.
Permanent ovarian treatment
As an alternative to injections, some women choose to have their ovaries removed in a laparoscopic bilateral salpingo-oophorectomy, a small surgery where the ovaries and both tubes are removed.
Removing the ovaries will bring on permanent menopause. This means you will no longer be able to fall pregnant naturally.
→ READ MORE: Targeted therapy for breast cancer
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More resources
A/Prof Cindy Mak, Breast Surgeon and Director of Breast Services, Chris O’Brien Lifehouse, Royal Prince Alfred Hospital, NSW; A/Prof Nick Murray, Consultant Medical Oncologist, Royal Adelaide Hospital and GenesisCare Adelaide, SA; Caroline Bennett, Consumer; Tamara Casey, Clinical Nurse Consultant, Breast Assessment Unit, Fiona Stanley Hospital, WA; A/Prof Joe Dusseldorp, Reconstructive Plastic Surgeon, Chris O’Brien Lifehouse, NSW; Lauren Lores, Consumer; Dr Linda Madigan, Breast Physician, Royal Adelaide Hospital, SA; Catherine Meredith, Consumer; Ash Mondolo, Breast Cancer Clinical Nurse Consultant, Mater Private Hospital, QLD; Chris Rivett, 13 11 20 Consultant, Cancer Council SA; Catrina Ross, McGrath Breast Care Nurse, Northern Sydney Local Health District, NSW; Prof Christobel Saunders AO, James Stewart Chair of Surgery and Director of Research, Melbourne Medical School, The University of Melbourne, VIC; Dr Janice Yeh, Radiation Oncologist, Peter MacCallum Cancer Centre, VIC; A/Prof Yvonne Zissiadis, Radiation Oncologist, Medical Director, GenesisCare WA and Adjunct A/Prof, Curtin University, WA.
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