Goserelin
GnRH agonist
Also Zoladex, Goserelin acetate, ICI 118630, Zoladex LA
- Evidence
- AStrong human evidence
- FDA status
- FDA approvedas of 2026-10-26
- Route
- Implant
- Studies cited
- 1 human0 animal or cell
A hormone-lowering implant used for prostate cancer, breast cancer and endometriosis. Controlled trials support these uses.
Sold for
Goserelin is a hormone-suppressing implant used in prostate cancer, premenopausal breast cancer and endometriosis, sometimes discussed as a way to protect ovaries during chemotherapy.
Studies say
Randomised trials show goserelin lowers sex hormones to post-menopausal or castrate levels and matches chemotherapy for survival in hormone-sensitive premenopausal breast cancer, which supports the approvals and the A grade.
Why grade A. Goserelin's approvals rest on randomised trials in prostate and breast cancer and endometriosis. The cited ZEBRA trial randomised 1,640 premenopausal women with node-positive early breast cancer to goserelin or CMF chemotherapy and found equivalent disease-free and overall survival in those with hormone-receptor-positive tumours. 12
FDA. Goserelin is FDA-approved as Zoladex, a subcutaneous implant first approved in 1989. Its labelled indications are palliative treatment of advanced prostate cancer, use with flutamide and radiotherapy in locally advanced prostate cancer, endometriosis, thinning of the uterine lining before ablation surgery, and palliative treatment of advanced breast cancer in pre- and perimenopausal women. 2
Written from 2 cited sources. Fact-checked 2026-10-27: 12 claims checked, 0 corrected. Last refreshed 2026-10-27. Not physician reviewed.
What this means for you
- What people take it for
- Prostate and breast cancer, and endometriosis
- Can a US doctor prescribe it?
- Yes, FDA approved for prostate cancer, endometriosis and other uses.
- Properly tested in people?
- Yes, in large controlled trials; one covered 1,640 women.
Evidence checklist
- Randomised controlled trial ZEBRA, goserelin versus CMFyes
- Human study over 100 people ZEBRA randomized 1,640 womenyes
- More than one research group Trials across prostate, breast, endometriosisyes
- Clinical outcomes, not surrogate markers Disease-free and overall survivalyes
- Human safety data beyond case reports Decades of label and trial datayes
Drawn from the cited studies below. A dash means the sources give no information.
What it is
Goserelin is a synthetic ten-amino-acid analog of gonadotropin-releasing hormone (GnRH), the hypothalamic hormone that tells the pituitary to release the signals driving testosterone and oestrogen production. It was developed by ICI Pharmaceuticals, later Zeneca and now AstraZeneca, and sold as Zoladex. 2
It comes as a small rod implanted under the skin of the abdomen with a needle, in one-month and three-month versions; it is not a liquid injection. The rod dissolves slowly and releases the peptide continuously. 2
How it works
Continuous exposure to a GnRH agonist does the opposite of what pulses of the natural hormone do. For the first week or two the pituitary releases a surge of luteinising hormone and testosterone or oestrogen rise, a flare that can briefly worsen cancer symptoms. After that the pituitary receptors downregulate, luteinising hormone falls, and the testes or ovaries stop producing their hormones. In men testosterone reaches castrate levels within about three to four weeks; in women oestrogen drops to post-menopausal levels. 2
What human research shows
The ZEBRA trial compared two years of goserelin against six cycles of CMF chemotherapy in 1,640 premenopausal women with node-positive early breast cancer. In the survival analysis published in 2003, women with oestrogen-receptor-positive tumours had equivalent disease-free and overall survival on either treatment, while women with receptor-negative tumours did worse on goserelin, as expected for a hormonal therapy. Goserelin caused menopausal symptoms; chemotherapy caused nausea, hair loss and infections. 1
The prostate cancer approvals rest on trials showing testosterone suppression equivalent to surgical castration and on a trial of goserelin plus flutamide with radiotherapy in locally advanced disease; the endometriosis and endometrial thinning indications rest on randomised comparisons showing symptom relief and reduced lining thickness. 2
| Study | Model | Finding |
|---|---|---|
| ZEBRA survival analysis, 2003 | Humans, n=1,640 premenopausal women with node-positive breast cancer, randomised goserelin versus CMF | Equivalent disease-free and overall survival in oestrogen-receptor-positive disease; inferior outcomes with goserelin in receptor-negative disease. 1 |
| Zoladex prescribing information, 2026 | FDA label summarising registration trials | Testosterone suppression to castrate levels in prostate cancer and symptom improvement in endometriosis supported the approved indications. 2 |
Safety
The common adverse effects follow from hormone suppression: hot flushes, loss of libido, erectile dysfunction in men, vaginal dryness in women, mood changes and, with long use, bone mineral loss. The initial flare can transiently worsen bone pain or urinary obstruction in men with metastatic prostate cancer, which is why an anti-androgen is sometimes started alongside. The label also carries warnings about hyperglycaemia, cardiovascular risk in men on androgen deprivation, and QT prolongation. Pregnancy must be excluded before use in women. 2
Questions for your clinician
- Would goserelin or chemotherapy suit my tumor receptor status?
- How will my bone density be followed during treatment?
- What happens to bone pain in the first weeks of prostate treatment?
Questions people ask
Is goserelin FDA-approved?
Yes, as Zoladex, since 1989. The current label covers advanced and locally advanced prostate cancer, endometriosis, endometrial thinning before ablation, and advanced breast cancer in pre- and perimenopausal women. 2
How does goserelin compare with chemotherapy in breast cancer?
In the 1,640-woman ZEBRA trial, two years of goserelin gave the same disease-free and overall survival as CMF chemotherapy in premenopausal women whose tumours were oestrogen-receptor-positive. In receptor-negative tumours chemotherapy was better. 1
Why do symptoms sometimes get worse at first?
A GnRH agonist initially stimulates the pituitary before shutting it down, so testosterone or oestrogen rises for a week or two. In men with metastatic prostate cancer this flare can briefly worsen bone pain or urinary symptoms. 2
How is goserelin given?
As a small solid implant placed under the skin of the abdomen through a needle, in a one-month or a three-month version, which dissolves and releases the drug steadily. 2
Citations
- Kaufmann 2003, European Journal of Cancer: survival analyses from the ZEBRA study, goserelin versus CMF in premenopausal node-positive breast cancer doi.org
- FDA 2026: Zoladex (goserelin implant) prescribing information accessdata.fda.gov