OFS either in association with tamoxifen (TAM) or an aromatase inhibitor (AI) improved disease-free survival in young women (≤35) and in those premenopausal women at higher risk of recurrence. However, its survival benefit remains largely unknown. In this study we characterize real-world use of adjuvant OFS from 2006 to 2015 and analyze its overall survival (OS) impact.
Retrospective observational cohort study of premenopausal women with Stage I-III hormone receptor-positive (HR+) breast cancer treated at one of 5 large centers in Portugal and diagnosed from 2006-2015. Study outcomes were use of OFS and OS. Pearson’s Chi2 test, logistic regression and Cox proportional hazards models were used.
Of 1717 eligible patients, 304 (17.3%) were treated with adjuvant OFS, of which 271 (15.4%) in combination with TAM and 33 (1.9%) with AI. Baseline characteristics differed by subgroups: patients treated with OFS were younger, had larger, less differentiated (grade III 16% vs 24% for OFS), more frequently HER2 positive (14% vs. 19% for OFS) tumors, and underwent more frequently mastectomy (48% vs 57% for OFS), radiotherapy (25% vs 31% for OFS) and (neo)adjuvant chemotherapy (73% vs 79% for OFS). Adjuvant OFS was used at least since 2006 with an increase in its use from 2014 onward (16% vs 25% since 2014), particularly for the combination with AI (0.4% vs 8% since 2014). In a multivariate model, characteristics associated with use of OFS included younger age and year of diagnosis ≥2014 (both p
In the real-world setting, a quarter of premenopausal women with early breast cancer were already treated with adjuvant OFS in 2014. After a median follow-up of 3 years, adjuvant OFS showed an OS benefit.
Clinical trial identification
Legal entity responsible for the study
Hospital de Santa Maria, Centro Hospitalar de Lisboa Norte
All authors have declared no conflicts of interest.