Menopausal side effects

Some treatments, especially chemotherapy and hormone-blocking therapy, can cause early menopause. This is defined as menopause that happens earlier than it would naturally.

For some women, menopause is temporary and ends after treatment is finished. For others, treatment results in permanent menopause.

Talk to your treating team about any menopause symptoms you are experiencing. Often you can take steps to manage them.

Menopause symptoms and breast cancer treatment explains ways to reduce their impact on your life and wellbeing.

Chemotherapy-induced menopause

When you have chemotherapy, your ovaries stop producing oestrogen. This causes your periods to stop and may be temporary or permanent.

Your chances of chemotherapy-induced menopause depend on several things including:

• your age – the closer you are to the usual age of menopause, the more likely menopause will start and be permanent
• the type of chemotherapy you are given
• the total amount of chemotherapy you receive over your full course of treatment
• the length of time you are treated with chemotherapy.

In younger women

In younger women, especially those under 35, menopause is often be temporary. Most types of chemotherapy make your periods less regular or stop entirely.

As oestrogen and progesterone levels fall, you may have menopausal symptoms such as hot flushes. You may have symptoms even if your periods continue.

If your periods return after treatment, your menopausal symptoms will go away.

The younger you are, the more likely that menopause will only be temporary. Usually, your periods will come back within one year of completing chemotherapy. They may come back regularly, or irregularly. This is unpredictable.

It is important to note that even if your periods temporarily stop, you are not necessarily infertile. If you are sexually active, you need to use a non-hormonal form of birth control, such as a condom, to avoid becoming pregnant during treatment.

In women over 40

The older you are when you have chemotherapy, the higher the risk that menopause will be permanent.

Menopausal symptoms may begin as your oestrogen and progesterone levels fall.

If you were already close to natural menopause and having symptoms ('perimenopausal'), they may get worse.

Ovarian suppression

For some premenopausal women with high-risk, HR+ breast cancer, reducing the amount of oestrogen produced by the ovaries can be helpful to stop breast cancer returning. There are 2 main options to do this.

Medication to suppress ovaries

Doctors may recommend goserelin (Zoladex). This temporarily shuts down the ovaries and stops them from producing oestrogen.

Given monthly via injection, Zoladex reduces the amount of oestrogen in your body, causing menopause. Once you stop this medication, your ovaries usually begin to work again, unless you have gone through menopause in this time.

Surgery to remove ovaries

Sometimes doctors recommend removing both ovaries (‘bilateral oopherectomy’). Generally this is for those with a high risk of getting cancer again such as:

• Women with a strong family history of breast cancer
• Women with a faulty gene e.g. BRCA1 or BRCA2.

Having both ovaries removed causes immediate and permanent menopause. This can result in sudden and severe menopausal symptoms.

Hormone-blocking therapy

People diagnosed with HR+ breast cancer are usually prescribed hormone-blocking therapy. This reduces the amount of oestrogen in your body.

Tamoxifen is the therapy usually given to premenopausal women. It does not induce menopause, but causes similar side effects, such as hot flushes and mood changes. It's possible to have monthly periods when you are on tamoxifen although they may be irregular. Some women do not have periods at all.

Aromatase inhibitors decrease how much oestrogen your skin and fat cells produce. These drugs are letrozole (Femara), anastrazole (Arimidex) and exemestane (Aromasin). They may also cause side effects like menopause, such as hot flushes and joint aches and pains. Aromatase inhibitors do not work in premenopausal women. They often have these tablets in combination with monthly Zoladex injections.

In younger women

Treatment can affect your periods, temporarily or permanently. You may experience symptoms of menopause, or menopause may start.

In women diagnosed with breast cancer under 50, about 60% go through menopause because of treatment. Other women may experience temporary menopause.

It’s important you know what to expect. Ask your doctor if your treatment might put you into early menopause.

If your menopause is permanent, you will be unable to have children naturally after treatment.

In women over 40

Hormone-blocking therapy can make any symptoms you have worse.