# Goserelin 3-month depot shows non-inferiority to the monthly formulation in U.S. patients with premenopausal breast cancer: a real-world evidence study

## TL;DR

A real-world study shows that a 3-month goserelin dose is as effective as the monthly dose for premenopausal breast cancer patients.

## Contribution

This study provides real-world evidence supporting the non-inferiority of 3-month goserelin over the monthly formulation.

## Key findings

- 12-month event-free survival was 79.2% for 3-month goserelin and 76.6% for monthly goserelin.
- Non-inferiority was observed in both early-stage and metastatic breast cancer patients.
- The treatment difference was within the non-inferiority margin of −15%.

## Abstract

Clinical trials demonstrated every 3-month goserelin 10.8 mg to be non-inferior to monthly goserelin 3.6 mg in premenopausal patients with ER-positive breast cancer. However, real-world studies comparing 3-month goserelin 10.8 mg with monthly goserelin 3.6 mg are scarce.

Electronic medical records from the ConcertAI Patient360™ database were analyzed in U.S. patients exposed to goserelin 3.6 mg or 10.8 mg post-breast cancer diagnosis. Inverse probability of treatment weighting (IPTW) was used to ensure the comparability between the two cohorts (goserelin 3.6 mg and goserelin 10.8 mg). The non-inferiority of goserelin 10.8 mg compared with goserelin 3.6 mg was assessed by 12-month real-world event-free survival (rwEFS) rates (− 15% margin) for the overall group of patients and separately for patients with early-stage/locally advanced and metastatic breast cancer.

A total of 575 patients received goserelin 3.6 mg and 123 received goserelin 10.8 mg. Goserelin 10.8 mg was non-inferior to goserelin 3.6 mg based on observed 12-month rwEFS rates (79.2% versus 76.6%, respectively; treatment difference 2.7%). Goserelin 10.8 mg was observed to be non-inferior in patients who initiated goserelin in early-stage/locally advanced (treatment difference − 2.3%) and metastatic (treatment difference 10.4%) breast cancer.

This real-world analysis indicates that 3-month goserelin 10.8 mg is non-inferior to monthly 3.6 mg among premenopausal women with breast cancer in terms of 12-month rwEFS rate. These findings may support the use of the 3-month goserelin 10.8 mg as an alternative treatment option to monthly goserelin 3.6 mg for this patient population.

The online version contains supplementary material available at 10.1007/s10549-025-07656-z.