OFS plus AI or SERM vs. SERM alone in premenopausal women with hormone receptor-positive breast cancer: a prospective cohort study using the real-world database

Background Ovarian function suppression (OFS) plus other endocrine treatment was recommended to hormone receptor (HR)-positive breast cancer by some guidelines recently. We performed this study to validate the survival benefits of OFS plus aromatase inhibitors (AI) or selective estrogen receptor modulators (SERM) in the real world. Methods All premenopausal, HR-positive breast cancer patients diagnosed between 1996 and 2017 were identified. Eligible patients were classified into three groups according to their adjuvant endocrine treatment, including OFS plus AI, OFS plus SERM and SERM alone. The primary outcome is invasive disease-free survival (iDFS), whereas the secondary outcome is overall survival (OS). Cox proportional hazards models and propensity score adjusted models were used to compare the survival benefits in three groups. Results We included 2838 patients, of which 246 received OFS plus AI, 175 received OFS plus SERM, and 2417 received SERM alone. Compared with SERM alone, OFS plus AI was associated with an improved iDFS (HR 0.59, 95% CI 0.36–0.96) and OS (HR 0.26, 95% CI 0.08–0.85). OFS plus SERM, however, was not significantly associated with extended iDFS or OS. Among patients older than 40 years old, OFS plus AI was more effective than OFS plus SERM (HR 0.38, 95% CI 0.17–0.88) or SERM alone (HR 0.44, 95% CI 0.23–0.84) in terms of iDFS. Conclusions Our findings suggest that OFS plus AI treatment may extend both iDFS and OS among premenopausal patients with hormone receptor-positive breast cancer in the real world.