Aromatase inhibitors plus ovarian function suppression versus tamoxifen plus ovarian function suppression for premenopausal women with early stage breast cancer: a systematic review and meta-analysis

In the NCCN guidelines version 1.2019, aromatase inhibitors (AIs) or tamoxifen (TAM) for 5 years plus ovarian function suppression (OFS) were recommended for premenopausal breast cancer patient who has higher risk of recurrence. The meta-analysis established a comparison of the curative effect of two adjuvant endocrine therapies. In order to obtain randomized controlled trials (RCTs) related to this metaanalysis, PubMed and Embase database were searched systematically in English during May 2019. Two reviewers screened the articles and extracted data based on the criteria recommended by the Cochrane collaboration for evaluating evidence in RCTs. The first outcome was disease-free survival (DFS). Overall survival (OS) was the other endpoint. Hazard ratios (HRs) with 95% confidence intervals (CIs) were pooled utilizing fixed-effect model. The heterogeneity of this study has been described by Cochran's Q and the I2 statistics. Three RCTs which involved 7,203 premenopausal women with breast cancer were available in this meta-analysis. Pooled HRs showed that there was not difference between AIs plus OFS and TAM plus OFS in DFS (HR =0.87, 95% CI: 0.66-1.14, P=0.30). No statistical differences were found in OS between the two adjuvant therapies (HR =1.22, 95% CI: 0.75-1.99, P=0.43). Based on the included studies, there were no statistical differences between AIs plus OFS and TAM plus OFS in DFS and OS.