Menopause and Tamoxifen

Menopause is a natural part of getting older and for most women, it occurs between the ages of 45 and 55. It can cause a variety of physical and psychological symptoms including hot flushes, loss of libido and mood changes.

Ageing also increases the risk of breast cancer. The estimated lifetime risk of a female being diagnosed is 1 in 71 and 80% of breast cancer cases occur in women over 502.

This means many women may find themselves in the challenging situation of navigating menopause at the same time as breast cancer treatment.

Tamoxifen is a medication used in the treatment of some breast cancers. Its side effects are similar to menopause symptoms, so it isn’t always easy to determine their root cause. In this guide, we explore the relationship between menopause and tamoxifen so that those prescribed this medication know what to expect.

What is tamoxifen?

Tamoxifen is a hormonal therapy medication. It belongs to a group of drugs called Selective Oestrogen Receptor Modulators (SERMs). It was first synthesised in 1962 and was originally intended to be used as a contraception but when found to be unsuitable for that purpose, it became an effective cancer treatment. It is primarily used in the treatment of oestrogen receptor-positive (ER-positive) breast cancers but is also used to treat other types of cancer3.

When is tamoxifen given?

Tamoxifen is used in the treatment of breast cancer in both males and females and can be prescribed to women in premenopause, perimenopause and postmenopause. There are several situations where Tamoxifen may be prescribed4:

As an adjuvant (additional) therapy following surgery or radiation for primary breast cancer to reduce the risk of recurrence or spreading.
Occasionally, Tamoxifen may be used as a first-line treatment for breast cancer when surgery is not possible or needs to be delayed.
Before surgery (neo-adjuvant or primary therapy) to shrink a larger breast cancer.
To treat local recurrence breast cancer.
To treat locally advanced breast cancer (LABC).
To treat metastatic breast cancer (secondary breast cancer).
To reduce the risk of cancer developing in high-risk individuals due to family history.

How does tamoxifen work?

Oestrogen-receptive breast cancers are stimulated to grow by the naturally occurring sex hormone oestrogen. Tamoxifen works by attaching to the oestrogen receptors on cancer cells, blocking oestrogen from being able to attach. This means that the oestrogen cannot tell the cancer to grow and in preventative treatment, develop at all5.

How is tamoxifen taken?

Tamoxifen is usually taken as an oral tablet, but it can be prescribed as a liquid for people who have difficulty swallowing. It's taken daily, at the same time each day5.

How long tamoxifen is taken depends on the situation.

For the treatment of early breast cancer, most people take it for five years, although it can be taken for up to 10 years.
When used to reduce the risk of breast cancer, it’s normally prescribed for 5 years.
If taking tamoxifen for secondary breast cancer, it can be taken for as long as it is helpful6.

Does tamoxifen cause menopause?

No, tamoxifen does not induce menopause like other cancer treatments, such as chemotherapy, can. It can, however, cause side effects that are akin to menopause symptoms, including making periods lighter or stopping them altogether. Sometimes periods will return when tamoxifen is stopped, although this can take several months5.

Research indicates that while there may be a slightly increased risk of premature menopause from tamoxifen in the oldest group of premenopausal breast cancer patients, for women under 45, there is not a substantial risk. Even for older women who are still menstruating, evidence suggests that the increased risk of menopause from tamoxifen therapy is approximately 10% greater than in women who aren’t prescribed it7.

Side effects of tamoxifen

The side effects of tamoxifen are similar to the symptoms produced by menopause. This is because of tamoxifen’s influence on oestrogen. These symptoms can become less frequent or severe over time, but this does not mean that they can’t still be difficult to manage. Tamoxifen has some common side effects that more than 10 in 100 people experience7,8. These include:

Hot flushes
Night sweats
Sleep disturbance
Vaginal irritation, including dryness and itching
Vaginal discharge or bleeding
Fluid retention, particularly in the hands or legs
Nausea and sickness
Fatigue
Skin changes including dryness, itching or rash
Mood changes and depression

This medication can also induce some occasional side effects that happen in between 1 and 10% of people7,8. These include:

Allergic reaction
Hair thinning or loss
Lightheadedness
Headaches
Constipation
Diarrhoea
Leg cramps
Muscle aches
Changes to the sense of taste
High blood triglyceride levels
Anaemia
A tingling or prickling sensation in the hands and feet

Tamoxifen also has some rarer, yet more serious side effects5 including:

Endometrial cancer
Blood clots
Stroke
Liver problems
Cataracts

It can also cause serious birth defects. Therefore, it is important to not become pregnant while taking tamoxifen or for at least 9 months afterwards6.

Is tamoxifen safe to take with HRT?

Research has indicated that there are no significant adverse interactions between tamoxifen and HRT, suggesting that they are safe to take together9.

However, women who have had breast cancer aren’t usually recommended HRT, particularly if they have had hormone-receptive positive breast cancer as it may increase the risk of cancer recurrence10.

Can you take tamoxifen with other medications?

Many medications can interact with tamoxifen and there is some evidence to suggest that certain drugs may make tamoxifen less effective11. You should always check with your prescriber or pharmacist if you’re taking any other medications.

Some herbal supplements can also impact the effectiveness of tamoxifen treatment11. These are not usually harmful if present in the food you eat as part of a normal, balanced diet but if you’re taking supplements, you should check with your doctor whether you can continue to use them when prescribed tamoxifen.

Further, it is recommended to limit or avoid alcohol when taking tamoxifen as alcohol consumption can potentially decrease the effectiveness of this cancer treatment11.

Can you take Tamoxifen after menopause?

Tamoxifen can be prescribed to postmenopausal women. As with all medications, there are some risks. For example, the relative risk of endometrial cancer in women taking tamoxifen is about 2 to 4 times higher than for postmenopausal women not taking tamoxifen12.

However, in almost all cases of oestrogen receptor-positive early-stage breast cancer, and all instances of metastatic breast cancer, the benefits of tamoxifen treatment outweigh the risks12.

Going through significant life events such as menopause and breast cancer can be really tough, but you don't have to go through them alone. At Menopause Care, we have a dedicated team of menopause specialists who are here to empower you to make the right choices for your own well-being. When you talk to one of our doctors, you can be assured that they’ll listen to your concerns and discuss your unique symptoms and circumstances at length. With evidence-based guidance and personalised treatment recommendations, they’ll work with you to improve your quality of life. If you need some support, book a consultation with a menopause doctor.

DisclaimerAt Menopause Care, we ensure that everything you read in our blog is medically reviewed and approved. However, the information provided is not meant to replace professional medical advice, diagnosis, or treatment. It should not be relied upon for specific medical advice.

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