Goserelin

Zoladex, Zoladex LA, ICI 118630, goserelin acetate

Sexual health, hormones & signalling

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Note on this profile. Goserelin is an approved prescription medicine in the US, EU, UK, Australia, South Africa and many other countries, not a research-only compound. This page explains the published science. Use outside a prescription carries real risks discussed below.

1What it is

Goserelin is a GnRH superagonist developed by ICI (later AstraZeneca) in the late 1970s and launched in 1987 as Zoladex. Its distinguishing feature is not the peptide but the delivery: it is embedded in a small rod of biodegradable lactide-glycolide polymer that is injected under the skin of the abdomen with a pre-loaded 16-gauge needle and dissolves over one or three months. That made it the first long-acting depot GnRH and it remains a standard hormone therapy in prostate cancer, premenopausal breast cancer, endometriosis and before uterine surgery. The US rights now sit with a smaller specialty company; AstraZeneca retains it in many other markets.

Community or self-directed use is essentially absent — the product is an implant placed by a clinician.

2How it's thought to work

Identical in principle to the other (see Buserelin, #211). After an initial LH/FSH surge over 1–2 weeks, pituitary GnRH receptors are down-regulated and testosterone falls to castrate levels by about day 21; oestradiol in women falls to postmenopausal levels within about 3 weeks. Effects reverse after the implant is exhausted, typically over 2–3 months, though recovery can be slower after prolonged use or in older men.

A GnRH agonist implanted under the skin. Constant stimulation of the pituitary receptor first raises LH and sex hormones, then exhausts the response, and the ovary or testis loses its instruction.Schematic — not to scale

3What the research shows

Advanced prostate cancer

Early randomised trials showed equivalence to orchidectomy in response and survival (Kaisary 1991, Br J Urol; Vogelzang 1995, Urology). The 10.8 mg 3-monthly formulation achieved equivalent testosterone suppression to the monthly implant (Dijkman 1995, J Urol †). [5]

Locally advanced prostate cancer with radiotherapy

EORTC 22863 randomised 415 men to radiotherapy alone or with 3 years of goserelin: 5-year overall survival 78% vs 62% (Bolla 1997, NEJM; 10-year follow-up Bolla 2010, Lancet Oncol). This trial established long-term androgen deprivation alongside radiotherapy as standard of care for high-risk disease. [1][2]

Premenopausal breast cancer

ZEBRA randomised 1,640 premenopausal women with node-positive early breast cancer to 2 years of goserelin or CMF chemotherapy: disease-free survival was equivalent in hormone-receptor-positive disease, with chemotherapy superior in receptor-negative disease (Jonat 2002, J Clin Oncol). Zoladex is licensed for advanced hormone-receptor-positive breast cancer and, in some countries, as adjuvant ovarian suppression. [3]

Ovarian protection during chemotherapy

POEMS/SWOG S0230 randomised 257 premenopausal women with hormone-receptor-negative breast cancer to chemotherapy with or without goserelin: ovarian failure at 2 years was 8% vs 22% and more pregnancies occurred in the goserelin arm (Moore 2015, NEJM). This is a widely cited but still debated use. [4]

Endometriosis and pre-operative fibroid/endometrial thinning

Six-month courses reduce lesion volume and pain comparably to danazol; a single implant before endometrial ablation thins the lining and improves procedural outcomes (Donnez 1997; label trials †).

4Reported side effects and interactions

Literature-reported

hot flushes (very common), loss of libido, erectile dysfunction, gynaecomastia and breast tenderness in men; vaginal dryness, headache, mood change and bone loss in women; injection-site bruising or haematoma (occasionally serious, including vascular injury from the large needle, which prompted a label warning); tumour flare in the first weeks with possible ureteric obstruction or spinal-cord compression in men with metastases. Long-term androgen deprivation is associated with bone fracture, diabetes, cardiovascular events and QT prolongation.

Community-reported

essentially none documented outside prescribed use.

Theoretical. pituitary apoplexy has been reported very rarely after first dose in people with undiagnosed pituitary adenomas (class effect).

Interactions. additive QT-prolonging risk with antiarrhythmics and some antipsychotics; concurrent anti-androgens for flare cover; glucose-lowering drugs may need adjustment over long courses.

Markers researchers commonly monitor

Drawn from label and oncology guideline monitoring:

Marker	Why it's watched
Testosterone and PSA (men)	confirms castrate suppression and tumour response; a rising PSA at castrate testosterone signals castration resistance.
Oestradiol, LH, FSH (women)	confirms ovarian suppression; relevant when combined with an aromatase inhibitor, which requires full suppression.
Bone mineral density (DEXA)	baseline and periodic for courses beyond 6 months.
HbA1c, lipid panel, blood pressure, weight	metabolic consequences of long-term androgen deprivation.
ECG (QTc)	in men with cardiac history or on QT-prolonging co-medication.
Haemoglobin	mild anaemia is common under long-term androgen deprivation.

Free for everyone. Safety information is never behind a paywall.

5Reconstitution and handling

A pre-filled implant-and-applicator unit; no or calculation is involved. Placed subcutaneously in the anterior abdominal wall below the navel by a trained clinician, avoiding the inferior epigastric vessels. The calculator is not applicable.

6Commonly studied alongside

Bicalutamide or flutamide (flare cover and combined androgen blockade), radiotherapy (EORTC 22863), tamoxifen or aromatase inhibitors (ovarian suppression in breast cancer), buserelin (#211), histrelin (#213), degarelix (#214), and the other GnRH analogue profiles (#102–#108).

Informational cross-links. Not stack recommendations.

7Regulatory status by region

Region	Status (checked —)
United States	FDA-approved (Zoladex 3.6 mg and 10.8 mg): prostate cancer palliation; with flutamide and radiotherapy for locally advanced disease; endometriosis, endometrial thinning and advanced breast cancer (3.6 mg); 10.8 mg indications in women †
European Union	Nationally authorised in all major markets (Zoladex / Zoladex LA)
United Kingdom	MHRA-licensed; prescription-only
Australia	TGA-registered (Zoladex 3.6 mg and 10.8 mg); PBS-listed
South Africa	SAHPRA-registered; prescription-only
Sport (WADA)	Prohibited in males under S2 (goserelin named among LH-releasing factors); not prohibited in females

8Open questions

Whether GnRH antagonists reduce cardiovascular events compared with in men with existing heart disease (PRONOUNCE was inconclusive; see Degarelix, #214).
Intermittent versus continuous androgen deprivation: non-inferiority remains debated for metastatic disease.
How durable fertility preservation is after goserelin-protected chemotherapy.

9References

1Bolla M et al. (1997). Improved survival in patients with locally advanced prostate cancer treated with radiotherapy and goserelin. NEJM. PubMed · DOI
2Bolla M et al. (2010). External irradiation with or without long-term androgen suppression for prostate cancer with high metastatic risk: 10-year results of an EORTC randomised study. Lancet Oncol. PubMed · DOI
3Jonat W et al. (2002). Goserelin versus cyclophosphamide, methotrexate, and fluorouracil as adjuvant therapy in premenopausal patients with node-positive breast cancer: the ZEBRA study. J Clin Oncol. PubMed · DOI
4Moore HCF et al. (2015). Goserelin for ovarian protection during breast-cancer adjuvant chemotherapy (POEMS). NEJM. PubMed · DOI
5Kaisary AV et al. (1991). Comparison of LHRH analogue (Zoladex) with orchiectomy in patients with metastatic prostatic carcinoma. Br J Urol. PubMed · DOI
6Zoladex (goserelin acetate implant) US prescribing information (current label). PubMed

References are being resolved to PubMed/DOI identifiers; links search PubMed for the citation until then.

† Being confirmed by our reviewers against current sources.

10Community

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Self-reported side effects Phase 2

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11Page history

31 Oct 2026Profile published — awaiting medical review

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