Aromatase inhibitors versus tamoxifen in premenopausal women with oestrogen receptor-positive early-stage breast cancer treated with ovarian suppression: a patient-level meta-analysis of 7030 women from four randomised trials

This EBCTCG meta-analysis investigated whether pre-menopausal women treated with ovarian suppression benefited from aromatase inhibitors (AIs). Meta-analysis was performed from individual patient data from RCTs (ABCSG XII, SOFT, TEXT, and HOBOE trials) comparing AIs vs. tamoxifen in pre-menopausal women with ER+ breast cancer receiving ovarian suppression. Data analysis was performed for 7030 women with ER+ breast cancer enrolled between 1999 to 2015 (median follow up of 8 years). Breast cancer recurrence rate was lower for women allocated to AI as opposed to tamoxifen (RR 0.79; p=0.0005). The main benefit was seen in years 0-4 (RR 0.68; p<0.0001), with a 3.2% absolute reduction in 5 year recurrence risk (6.9% vs. 10.1%). No further benefit was seen in years 5-9 or beyond year 10. Distant recurrence was reduced with AIs (RR 0.83; p=0.018). No significant differences were observed for breast cancer mortality (RR 1.01; p=0.94), death without recurrence (1.3; p=0.34), or all-cause mortality (RR 1.04; p=0.68). More bone fractures were observed with AIs when compared to tamoxifen (6.4% vs. 5.1%; p=0.017). Endometrial cancer was rare (0.2% AI group vs. 0.3% tamoxifen group; p=0.14). This meta-analysis shows that using AIs rather than tamoxifen in pre-menopausal women receiving ovarian suppression reduces breast cancer recurrence risks. Longer term follow-up is required to assess any impact on survival outcomes.    

Classifications: Adjuvant & Neoadjuvant Treatment

Keywords: Endocrine Therapy