Ovarian suppression to protect fertility during chemotherapy

Chemotherapy for breast cancer can damage the ovaries, sometimes causing early menopause and loss of fertility, especially in women over their mid thirties. One approach to reduce this damage is ovarian suppression during chemotherapy, using medicines called GnRH agonists, such as goserelin or leuprolide. These are given as injections, usually starting at least a week or two before the first chemotherapy dose and continuing every four weeks until chemotherapy finishes. They temporarily switch off the ovaries, putting them into a resting state that may make them less vulnerable to chemotherapy. Several randomised trials, including the POEMS study in women with hormone receptor negative breast cancer, and pooled analyses of many trials, have shown that women who received GnRH agonists during chemotherapy were less likely to develop premature ovarian insufficiency, meaning periods stopping permanently, and in some studies more women later became pregnant. Because the evidence on future pregnancy is less certain than the evidence on protecting ovarian function, guidelines generally recommend that ovarian suppression should not replace egg or embryo freezing for women who want to preserve fertility, but may be offered as an additional option, or when freezing is not possible. The decision should be made with your oncologist.

It is temporary

The ovaries usually start working again after the injections stop, though chemotherapy may still have reduced egg reserve.

Side effects are menopausal

Hot flushes, sweats and vaginal dryness are common while ovaries are switched off.

Timing matters

Injections are ideally started before chemotherapy begins.

Ovarian suppression is a helpful option for some women, but it is important to understand its limits.

Evidence on pregnancy is less certain

Trials were designed mainly to measure periods returning, not live births, so the effect on having a baby is less clear.

It does not stop all damage

Chemotherapy can still reduce egg reserve even with ovarian suppression.

Hormone-positive cancer considerations

Early concerns about using GnRH agonists in hormone receptor positive cancer have eased, and they are widely used, but decisions are individual.

Side effects affect quality of life

Menopausal symptoms during treatment can be troublesome.

What this page cannot tell you

It cannot tell you whether this suits you. Your oncologist and fertility specialist can.

Switching off the ovaries causes temporary menopause-like symptoms.

Hot flushes

Layered cotton clothing, fans, cool drinks and avoiding spicy food and alcohol can help. Your doctor may suggest non-hormonal medicines if severe.

Vaginal dryness

Non-hormonal moisturisers and lubricants ease discomfort.

Mood and sleep

Regular exercise, sleep routines and support help. Tell your team about low mood.

Injection site

Mild bruising or soreness where the implant is given is common.

Bone health

Longer-term suppression can thin bones, so bone health may be checked if continued.

Several randomised trials have tested whether switching off the ovaries during chemotherapy protects them. Understanding what they measured helps put the results in context.

The POEMS study

This trial included premenopausal women with hormone receptor negative early breast cancer. Women who received goserelin with chemotherapy were less likely to have ovarian failure two years later, and more women in the goserelin group went on to have a pregnancy.

Other trials

Studies that also included women with hormone receptor positive cancer, such as the Italian PROMISE trial, found fewer women developing early menopause when ovarian suppression was added.

Pooled analyses

When results from many trials were combined, ovarian suppression reduced the risk of premature ovarian insufficiency and was associated with more post-treatment pregnancies, with no clear effect on how well the cancer treatment worked.

What was not measured well

Few trials followed large numbers of women through attempts to conceive, so the effect on having a baby remains less certain than the effect on periods.

How guidelines use the evidence

Major guidelines consider ovarian suppression a reasonable option to protect ovarian function, while recommending egg or embryo freezing for women who want the best chance of future pregnancy.