111P - Goserelin 3 monthly depot is noninferior to Goserelin monthly depot in the treatment of Breast Cancer: A Real-World Evidence Study

Background

Goserelin 10.8 mg 3-monthly depot demonstrated non-inferior to 3.6 mg monthly depot in randomized clinical trials. This first retrospective, observational, non-inferiority, real-world study compared effectiveness of goserelin 10.8 mg 3-monthly depot to 3.6 mg monthly depot in breast cancer (BC) patients.

Methods

Data were extracted from electronic records of pre- and perimenopausal BC patients who received the first dose of goserelin between January 2015 to December 2022 at Sun Yat-sen University Cancer Center, China. The primary endpoint was non-inferiority analysis of proportion of patients with serum estradiol (E₂) suppression. Secondary endpoints included overall survival (OS), disease-free survival (DFS) for early BC, progression-free survival (PFS) for advanced BC. Propensity score matching (PSM) was used to balance baseline characteristics considering age, prior chemotherapy, and BMI as covariates with caliper of -25%. P <0.05 was statistically significant. Non-inferiority was calculated using the risk difference (RD) by Miettinen-Nurminen method. Multivariate logistic regression analyzed the independent factors (age, chemotherapy, BMI, stage, and radiotherapy) associated with E₂ suppression.

Results

In total, 240 (goserelin 10.8 mg, n = 143; goserelin 3.6 mg, n = 97) HR⁺ BC patients with E₂ tests were included. Post PSM, 96 patients in each group were considered for the primary analysis. E₂ suppression rate was 98.96% in goserelin 10.8 mg and 92.71% in goserelin 3.6 mg with a RD of 0.065 (95%CI: 0.021, 0.135; P=0.0187), confirming the non-inferiority between the goserelin 10.8mg and goserelin 3.6mg groups at a margin of -15%. None of the factors showed significant association with E₂ suppression. Goserelin 10.8 mg vs 3.6 mg 5year OS, DFS, and 3.2year PFS rates were 96.6% vs 93.8%, 99.0% vs 96.7%, and 77.1% vs 80.0%, respectively.

Conclusions

Goserelin 10.8 mg was non-inferior to goserelin 3.6 mg in peri- and premenopausal BC patients in terms of E₂ suppression.

Legal entity responsible for the study

The authors.

Funding

This research was supported by National Natural Science Foundation of China (No.81974444, Xinhua Xie; No.82203569, Hao Wu).

Disclosure

All authors have declared no conflicts of interest.