Goserelin: Uses, Mechanism, and Side Effects

Anyone starting hormone therapy for prostate or breast cancer, or being treated for endometriosis, usually wants to know how the drug works and what to expect. Goserelin is a well established option in each of these areas, with decades of clinical use behind it.

Key takeaways

• Goserelin is a synthetic GnRH agonist sold under the brand name ZOLADEX.
• It is approved for prostate cancer, advanced breast cancer in pre- and perimenopausal women, endometriosis, and endometrial thinning before ablation.
• More than 430 clinical trials have studied goserelin across these and related uses.
• Reported adverse events most often involve disease progression, fatigue, and low neutrophil counts, reflecting its use in cancer populations.
• No boxed warning is listed on the current label.

What Goserelin Is

Goserelin is a synthetic decapeptide analogue of gonadotropin releasing hormone (GnRH). When given in its biodegradable formulation, it works by inhibiting the release of gonadotropins from the pituitary gland. This reduces the body's production of sex hormones, which is the basis for its use in hormone-sensitive conditions. Laboratory and animal studies have shown that goserelin can slow or reverse growth in hormone-responsive tumor models.

What Goserelin Is Approved For

Under the brand name ZOLADEX, goserelin has several approved uses. It is indicated in combination with flutamide for locally confined prostate carcinoma (Stage T2b-T4), and for palliative treatment of advanced prostate carcinoma. It is also approved for the management of endometriosis, as an endometrial-thinning agent before endometrial ablation for dysfunctional uterine bleeding, and for palliative treatment of advanced breast cancer in pre- and perimenopausal women. The current label does not carry a boxed warning.

What the Evidence Shows

Goserelin has been studied in more than 430 registered clinical trials. One completed trial examined ZOLADEX combined with tamoxifen in breast cancer. A completed Phase 3 trial compared a biosimilar candidate, LY01005, against ZOLADEX in breast cancer patients, while a separate Phase 1 trial testing goserelin alongside another agent in advanced breast cancer was terminated.

Reported Side Effects

Adverse event reports submitted for goserelin most frequently mention death and malignant neoplasm progression, findings that likely reflect its use in patients with advanced cancer rather than a direct drug effect. Fatigue and asthenia are also commonly reported, along with bone metastases. Neutropenia, nausea, and hot flush round out the most frequently reported terms. These figures represent counts of submitted reports, not confirmed rates of incidence, and they do not establish that goserelin caused the event.