Goserelin Side Effects: What Studies Report

How goserelin adverse-event information is generated

Goserelin is an approved prescription medicine in the gonadotropin releasing hormone (GnRH) agonist class, dispensed and administered under medical supervision. A prescribing clinician decides whether and how it is used, and every personal question about tolerability, monitoring or suitability belongs with that clinician. This page summarises what published studies and regulatory-grade trial reports describe about adverse events, and it states plainly where structured adverse-event data were absent from the literature reviewed. Background on the molecule itself sits in the goserelin glossary entry, with mechanism covered in how goserelin works and indications in what goserelin is approved for.

Three kinds of evidence dominate. The first is randomised comparison of goserelin against another formulation of the same drug class, which produces the cleanest attribution because both arms received a GnRH agonist. The second is randomised oncology trials in which goserelin was a background component of endocrine therapy and the randomisation tested a different agent, so adverse-event tables describe the whole regimen rather than goserelin alone. The third is observational cohort work in populations receiving androgen deprivation therapy, where event rates are measured across a treatment class rather than a single product. Reading the adverse-event literature accurately means keeping those three designs separate.

Endocrine and hormone-suppression effects: What Studies Report

The pharmacologic purpose of goserelin in oncology is suppression of gonadal steroid production, and the measurable consequences of that suppression dominate how adverse events are described. A multicentre, randomised, open-label, phase III non-inferiority trial in Chinese patients with prostate cancer compared a goserelin microsphere formulation with a goserelin implant and used attainment and maintenance of castration-level testosterone as its efficacy endpoint, with safety assessed in parallel (PMID 37010251). Researchers in that trial reported that the safety findings of the two goserelin formulations were comparable, which is the expected pattern when both arms deliver the same active molecule (PMID 37010251).

In premenopausal breast cancer trials, goserelin was used to produce ovarian function suppression alongside tamoxifen or an aromatase inhibitor. The MONALEESA-7 phase III trial enrolled premenopausal and perimenopausal women with hormone receptor positive advanced breast cancer and gave goserelin to participants in both the ribociclib and placebo arms, so hormone-suppression effects appeared on both sides of the randomisation and could not be separated out as ribociclib toxicity (PMID 29804902). The same structural point applies to the RIGHT Choice trial, in which premenopausal women received goserelin as part of the endocrine therapy arm while the comparator arm received combination chemotherapy (PMID 38771995).

Detailed frequency tables for symptoms of oestrogen or testosterone withdrawal attributable to goserelin alone were not reported in the studies reviewed on this page. Where a reader wants event-by-event frequencies, the approved prescribing information for the product in a given jurisdiction is the document that carries that tabulation, and the prescriber is the person who interprets it for an individual.

Cardiovascular and metabolic signals: What Studies Report

Cardiovascular outcomes after androgen deprivation have been examined at the level of the drug class rather than one product. A 2022 review in European Heart Journal Cardiovascular Pharmacotherapy examined the cardiovascular effects of GnRH antagonists in men with prostate cancer and discussed how observed cardiovascular event rates compared with those seen under GnRH agonist therapy, while noting the limits of the available comparative evidence (PMID 33470403). That review described a research question rather than a settled conclusion, and it did not isolate goserelin from other agonists (PMID 33470403). Differences between the two mechanisms are discussed separately in goserelin compared with triptorelin.

Cardiac electrophysiology appears in the combination-therapy literature rather than in single-agent goserelin reports. In MONALEESA-7, where all participants received goserelin, QT interval prolongation was tracked as an adverse event of interest in the ribociclib arm (PMID 29804902). The NATALEE phase III trial likewise followed QT interval prolongation and liver-related events as adverse events of special interest in the ribociclib arm (PMID 38507751). These were regimen-level observations, and the published reports did not assign them to the GnRH agonist component.

Haematologic and regimen-level adverse events in combination trials: What Studies Report

Several large randomised trials used goserelin as background endocrine therapy, and their safety tables are therefore informative about the regimen as a whole. In MONALEESA-7, researchers reported that grade 3 or 4 neutropenia occurred far more often in the ribociclib plus endocrine therapy group, which also contained goserelin, than in the placebo plus endocrine therapy group (PMID 29804902). In the PALOMA-3 trial of palbociclib plus fulvestrant in hormone receptor positive advanced breast cancer, premenopausal and perimenopausal participants received goserelin for ovarian suppression, and the study reported neutropenia and leukopenia as the most frequent grade 3 or 4 adverse events in the palbociclib group (PMID 26030518).

The NATALEE trial design paper described the planned use of goserelin for ovarian suppression in premenopausal women and for androgen suppression in men receiving adjuvant ribociclib plus a nonsteroidal aromatase inhibitor in early breast cancer (PMID 37275963). The primary NATALEE report in the New England Journal of Medicine described neutropenia, liver-related events and QT interval prolongation among adverse events observed more often in the ribociclib arm than in the endocrine therapy alone arm (PMID 38507751). The final invasive disease free survival analysis published in Annals of Oncology reported that safety observations remained consistent with the earlier analysis of the same trial (PMID 39442617), and the 4-year outcome report in JAMA Oncology described safety findings consistent with previous analyses of that trial population (PMID 40996773). In RIGHT Choice, the comparison was between ribociclib plus endocrine therapy containing goserelin and combination chemotherapy, and the trial reported differences between the two arms in treatment related adverse events leading to discontinuation (PMID 38771995).

Population differences in reported adverse events: What Studies Report

Observational work has asked whether adverse events after androgen deprivation therapy are distributed evenly across patient groups. A 2025 cohort analysis published in JAMA Network Open examined racial differences in adverse events after androgen deprivation among veterans with prostate cancer and reported that event rates differed between racial groups in that cohort (PMID 41259022). That analysis described androgen deprivation as a treatment category rather than isolating any single agent, and as an observational design it describes associations within a defined health system population (PMID 41259022).

Where structured adverse-event data were absent

Several questions that readers commonly bring to a side-effect page were not answered by structured data in the studies cited here. The literature reviewed on this page did not provide frequency tables for injection site reactions with goserelin, did not provide bone mineral density or fracture incidence specific to goserelin, and did not provide long-term cognitive or mood outcome rates for goserelin considered on its own. Where a trial reported an adverse event, the event belonged to a regimen that usually included at least one other active drug (PMID 29804902, PMID 26030518). Absence of a figure in this summary means the verified source set did not report it, not that an event has been ruled out.

Study-by-study summary table

How to read these findings without over-reading them

Three cautions follow from the designs above. First, attribution is limited: in the breast cancer trials, goserelin sat inside a multi-drug regimen, so an adverse event listed in a safety table reflects the regimen (PMID 29804902). Second, class-level findings are not product-level findings, which is why a cardiovascular review of GnRH antagonists in men with prostate cancer answers a question about mechanisms rather than about one named agonist (PMID 33470403). Third, observational cohorts describe associations in the population studied, as in the veterans cohort that reported differing adverse event rates across racial groups (PMID 41259022).

Published trial descriptions also report study design details such as the scheduled administration interval, and those details belong to the trial protocol as executed by investigators rather than to any individual outside that setting (PMID 37010251). Monitoring decisions, management of any symptom, and the choice of whether a GnRH agonist is appropriate at all are made by the prescribing clinician.

This page is for educational purposes only and is not medical advice; consult a licensed physician about any symptom, medicine or treatment decision.

Related reading

• Goserelin glossary entry
• How goserelin works
• What goserelin is approved for
• Goserelin compared with triptorelin in the literature

References

• Efficacy and safety of LY01005 versus goserelin implant in Chinese patients with prostate cancer: a multicenter, randomized, open-label, phase III, non-inferiority trial (Chinese Medical Journal, 2023)
• Ribociclib plus endocrine therapy for premenopausal women with hormone-receptor-positive, advanced breast cancer (MONALEESA-7): a randomised phase 3 trial (The Lancet Oncology, 2018)
• Palbociclib in Hormone-Receptor-Positive Advanced Breast Cancer (The New England Journal of Medicine, 2015)
• Rationale and trial design of NATALEE: a Phase III trial of adjuvant ribociclib plus endocrine therapy versus endocrine therapy alone in patients with HR+/HER2- early breast cancer (Therapeutic Advances in Medical Oncology, 2023)
• Ribociclib plus Endocrine Therapy in Early Breast Cancer (The New England Journal of Medicine, 2024)
• A phase III trial of adjuvant ribociclib plus endocrine therapy versus endocrine therapy alone in patients with HR-positive/HER2-negative early breast cancer: final invasive disease-free survival results from the NATALEE trial (Annals of Oncology, 2025)
• Ribociclib Plus Endocrine Therapy in Hormone Receptor-Positive/ERBB2-Negative Early Breast Cancer: 4-Year Outcomes From the NATALEE Randomized Clinical Trial (JAMA Oncology, 2025)
• Final Results of RIGHT Choice: Ribociclib Plus Endocrine Therapy Versus Combination Chemotherapy in Premenopausal Women With Clinically Aggressive Hormone Receptor-Positive/Human Epidermal Growth Factor Receptor 2-Negative Advanced Breast Cancer (Journal of Clinical Oncology, 2024)
• The cardiovascular effects of gonadotropin-releasing hormone antagonists in men with prostate cancer (European Heart Journal Cardiovascular Pharmacotherapy, 2022)
• Racial Differences in Adverse Events After Androgen Deprivation in Veterans With Prostate Cancer (JAMA Network Open, 2025)