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HRT after breast cancer: the latest evidence
What do the results mean for me?
What to consider when making your decision
This information sheet discusses whether HRT is safe after a breast cancer diagnosis. It is important that you carefully consider this evidence and discuss the benefits and risks of HRT with your doctor.
HRT is a hormone treatment taken by some women to reduce symptoms of menopause. The hormones used are usually oestrogen and progestin (progestogen) combined, sometimes with testosterone added. Oestrogen-only HRT is given to women who have had a hysterectomy. This is because oestrogen increases the risk of endometrial cancer in those with an intact uterus when not balanced by progesterone.
There are also synthetic steroids available that act like hormones.
Until February 2004 it was not known whether HRT was safe for women who have had breast cancer. Then, a Scandinavian study (HABITS), which included Australian women, found an ‘unacceptably high risk' of the cancer recurring in breast cancer survivors who took HRT. Breast cancer survivors who took HRT had more recurrences of their original cancer and more new cancers in the other breast than survivors who did not take HRT. Of 434 survivors, 26 women in the group who took HRT had a recurrence or a new breast cancer, compared to seven in the group who did not take HRT (including two who were actually taking HRT despite being in this group).
HABITS was a randomised controlled trial, which means its results provide a high level of scientific evidence. It is unlikely that we will ever get stronger evidence than this. A trial is underway of the synthetic steroid, Tibolone, for women who have had breast cancer. Final results are expected by July 2006.
The results of the HABITS study confirm that taking HRT increases the risk of a new breast cancer. If you are thinking of taking HRT, or are already doing so, you should carefully consider the benefits and risks. Discuss HRT with your doctor.
Menopause can occur naturally, or because of breast cancer treatment such as tamoxifen. Menopause may cause various symptoms. HRT will reduce hot flushes, night sweats, urinary incontinence and vaginal irritation and dryness. For some women, HRT is the only treatment that helps with severe menopausal symptoms.
To treat vaginal dryness, creams or tablets containing oestrogens may be used in the vagina. This treatment is likely to be safe as only small amounts of oestrogen are absorbed into the bloodstream, although no studies have been done with women who have had breast cancer.
Studies with women who have not had breast cancer have shown that combined oestrogen--progestin HRT will occasionally be appropriate if fracture risk is high and other medicines are intolerable. Evidence also shows that combined HRT may slightly reduce the risk of bowel cancer. Discuss this with your doctor if your risk of these conditions is also high.
If you decide to take HRT and notice an unusual breast change or any unusual vaginal bleeding, you should see your doctor as soon as possible.
You have been treated for breast cancer and are concerned that taking HRT will increase your risk of breast cancer recurring.
As discussed above, the latest evidence suggests you will be at a significantly higher risk of a breast cancer recurrence or new breast cancer if you take HRT.
There is an increased risk of these diseases in women taking HRT. The Women's Health Initiative study (July 2002) found that for every 10,000 women taking combined HRT, there were seven more cases of heart disease, eight more breast cancers, eight more strokes, and eight more blood clots on the lungs for each year of treatment. (This study was done with women who had not had breast cancer.)
Known side effects include an increased risk of blood clots in the veins, particularly in the first 12 months of use (overall this risk is low). Inflamed veins and blood clots may occur with long-term use.
For women who have had breast cancer, regular mammograms are usually an important part of ongoing care. Some types of HRT can increase a woman's breast density. This can make it slightly harder to detect breast cancers by mammography.
See below.
There are many menopause-related products available in supermarkets and other outlets. There is very little scientific evidence about the benefits and risks of these products, and it is not always easy to be sure of the amount or dose of the ingredients. Any research that has been completed is likely to have been done with women who have not had breast cancer.
Black cohosh (a herb) is often used to treat menopausal symptoms. In a randomised controlled trial with breast cancer patients having hot flushes, no difference in relief was found between black cohosh and a placebo (sugar pills). There is currently not enough evidence to recommend its use. No long-term safety information is available.
Women's health services will have more detailed information about non-prescription remedies for problems related to menopause. There are also some prescription drugs that are alternatives to HRT for some conditions. An antidepressant from the group known as ‘selective serotonin receptor inhibitors' has been shown to improve menopausal symptoms in breast cancer survivors, although it can cause side effects. The dose needed to improve symptoms is about half that required to treat depression. If interested, speak to your doctor about this.
Non-drug alternatives include staying in a cool, well-ventilated environment; avoiding spicy foods, hot drinks and other stimulants; and relaxation and meditation. However, most of these have not been well tested. If you are using alternative therapies, it's important that you tell your doctor.
For most women at or around menopause, deciding whether to take HRT is not a simple process. If you are a woman with a personal history of breast cancer this decision is likely to be particularly difficult. Whichever way you decide, it's important to keep in touch with your doctor about any symptoms you are experiencing. You may want to keep up to date with information on the relationship between HRT and breast cancer via the National Breast Cancer Centre website (www.nbcc.org.au).
For further information contact the Cancer Council Helpline on 13 11 20.
