Goserelin (Zoladex) for breast cancer: the complete patient guide

Goserelin, often known by the brand name Zoladex, is a hormone treatment that switches off the ovaries for as long as it is given. It belongs to a group of medicines called LHRH or GnRH agonists. It comes as a tiny implant, about the size of a grain of rice, which a nurse or doctor places under the skin of the belly with a special needle, usually once every four weeks. The implant slowly releases the medicine and then dissolves. Goserelin acts on the pituitary gland in the brain, which normally sends signals telling the ovaries to make oestrogen. After a short initial surge, those signals are shut down, and within a few weeks oestrogen falls to levels similar to those after the menopause. In breast cancer, goserelin is mainly used for women who have not reached menopause and whose cancer is hormone receptor positive. It may be given after surgery together with tamoxifen or an aromatase inhibitor for women at higher risk of the cancer returning, or for advanced disease, often with an aromatase inhibitor and a CDK4/6 inhibitor. It is also sometimes used during chemotherapy to help protect the ovaries, and for men with breast cancer alongside other hormone treatment. Its effects, including periods stopping, are usually reversible after treatment ends, although age and earlier chemotherapy affect whether periods return.

A temporary, reversible menopause

Goserelin causes menopause-like changes that usually wear off after the injections stop.

Often part of a combination

In breast cancer it is rarely given alone; it makes other hormone treatments more effective or possible.

Side effects are mostly menopause symptoms

Hot flushes, sweats, vaginal dryness, mood changes and bone thinning are the main effects to plan for.

For the right women, adding goserelin lowers the chance of breast cancer returning or helps control advanced disease. It also brings real changes to daily life.

The benefit depends on risk

For women at low risk of the cancer returning, the extra benefit after surgery is small, and side effects may outweigh it.

Symptoms can be sudden

Menopause arrives within weeks rather than over years, which many women find harder to adjust to.

It is not reliable contraception

Pregnancy is unlikely but not impossible, so non-hormonal contraception is still advised.

What this page cannot tell you

It cannot tell you whether the benefit is worth the side effects for you. Your oncologist can discuss your own risk.

In breast cancer, goserelin is usually one part of a treatment plan.

With tamoxifen

Tamoxifen blocks oestrogen receptors while goserelin lowers oestrogen levels, giving a double effect for women at higher risk.

With an aromatase inhibitor

Letrozole, anastrozole or exemestane only work in premenopausal women when the ovaries are switched off. Teams often start goserelin a few weeks before the tablet, and may check oestradiol blood levels.

With CDK4/6 inhibitors

For advanced disease, goserelin plus hormone treatment may be combined with ribociclib, palbociclib or abemaciclib.