At a glance
| Brand | Zoladex |
|---|---|
| Mechanism | GnRH agonist followed by pituitary suppression |
| Delivery | Subcutaneous implant |
| Oncology roles | Defined prostate and advanced breast cancer uses |
| Gynecology roles | Endometriosis and endometrial thinning |
| Early effect | Transient hormone flare |
Overview
Goserelin is delivered through a subcutaneous implant that releases medicine over time. Sustained suppression of testosterone or ovarian estrogen can treat conditions driven by these hormones. The US Zoladex label includes defined prostate-cancer settings, palliative treatment of advanced breast cancer in premenopausal or perimenopausal women, endometriosis and endometrial thinning before ablation. Different implant presentations do not necessarily share every indication. Temporary ovarian suppression is a treatment effect rather than proof of permanent infertility, and neither absent menstruation nor suppressed hormone measurements should be treated as reliable contraception.
How it works
Goserelin initially activates pituitary GnRH receptors and briefly increases gonadotropin secretion. With continuous exposure, the pituitary response becomes suppressed, lowering LH and FSH and consequently testosterone or estradiol. This two-stage agonist effect differs from immediate receptor blockade by antagonists. Reduced sex-hormone signaling explains both activity against hormone-sensitive disease and adverse effects such as hot flushes and bone mineral loss.
Which uses are established?
The label includes advanced prostate cancer and a specified regimen with flutamide and radiotherapy for certain prostate tumors. Other indications include advanced breast cancer in premenopausal or perimenopausal women, endometriosis, and endometrial thinning before ablation. Treatment purpose and duration differ across these conditions.
Supporting sources [1]
Why does disease context matter?
Randomized clinical research has studied goserelin alone and with tamoxifen in advanced breast cancer. Those findings concern hormone-sensitive cancer populations and combinations. The current label describes separate evidence for prostate and gynecologic indications; one study cannot be used as a blanket efficacy estimate for all of them.
What risks accompany sustained suppression?
Initial tumor flare can worsen symptoms in prostate cancer. Other concerns include reduced bone density, hyperglycemia, cardiovascular risk, QT prolongation, depression and pregnancy-related harm. Implant administration can cause serious injection-site injury or bleeding. These risks require assessment according to the patient’s condition and treatment setting.
Supporting sources [1]
Is goserelin a permanent way to switch off hormones?
Its intended pharmacologic action is reversible suppression, although recovery varies with age, exposure and underlying disease. It should not be assumed to provide contraception. In endometriosis, the label limits the established treatment course because prolonged estrogen deprivation raises additional concerns, including bone loss.
Supporting sources [1]
Reading this profile
Jurisdiction: United States; indications and availability vary by formulation and country.. Molecular class: Synthetic GnRH agonist peptide in a biodegradable implant.
This profile was written with AI-assisted research and checked against the linked sources. It has not been represented as a clinician’s review. Evidence summaries describe the cited studies and products; they do not establish that a separately purchased preparation is equivalent.
Sources & references
Follow the original material. Product labels define specific formulations and uses; trial registration describes a study and does not by itself establish benefit.
- Zoladex — current US prescribing information ↗Regulatory source · Checked 2026-10-27
- Randomized goserelin with or without tamoxifen in advanced breast cancer ↗Original research · Checked 2026-10-27