Hormonal therapies to treat DCIS
Hormones are substances that occur naturally in the body. They act as chemical messengers, which influence the growth and activity of cells.
Hormonal therapies are treatments that reduce levels of certain hormones in the body or block their effects on cancer cells.
Hormonal therapies for DCIS are drugs that block the hormone oestrogen from attaching to breast cancer cells, or lower the level of oestrogen in the body. Oestrogen can encourage some breast cancer cells to grow.
Hormonal therapies are commonly prescribed for women with invasive breast cancer because they reduce the risk of breast cancer coming back. Hormonal therapies only work in women whose cancer cells have receptors for oestrogen. This is known as oestrogen-receptor positive (ER positive) breast cancer.
While doctors know that there are benefits of using hormonal therapy for DCIS, they don’t know exactly how useful this treatment is, so hormonal therapies are mainly only given in research trials.
Tamoxifen is a commonly used hormonal therapy. It’s widely used in women with early, invasive breast cancer who haven’t had their menopause and in some women who have.
Trials have shown that tamoxifen helps to reduce the risk of ER positive DCIS coming back. It can also reduce the risk of invasive cancer in both breasts. However, the amount of benefit isn’t clear so tamoxifen isn’t used routinely.
Some specialists recommend taking tamoxifen. Your specialist will explain the possible advantages of tamoxifen in your situation.
You may need time to talk things over with your doctor, nurse or family before making a decision.
Tamoxifen is taken daily as a tablet, usually for 3–5 years. Common side effects are:
hot flushes and sweats
vaginal dryness or an increased vaginal discharge
For many women, these side effects are mild and can reduce over time. But in some women, side effects can continue to be troublesome. If this happens, talk to your doctor or nurse. Some of the side effects of tamoxifen are similar to the symptoms of the menopause.
For women who’ve been through the menopause, tamoxifen can slightly increase the risk of womb (endometrial) cancer, blood clots in the leg and strokes. Although this sounds frightening, these effects are very rare. If they occur, they’re usually picked up very early when they can be successfully treated.
We have more information on tamoxifen. We also have more information on breast cancer and menopausal symptoms.
Aromatase inhibitors are another type of hormonal therapy. They block the production of oestrogen in women who’ve had the menopause. Aromatase inhibitors that are commonly used include:
Research has shown that these drugs can be used to treat DCIS and other trials are underway to find out which women should take them. Like tamoxifen, they only work for ER positive DCIS.
Your doctor or breast care nurse can tell you more about any trials that you may be suitable for.