Meta-analyses of phase 3 randomised controlled trials of third generation aromatase inhibitors versus tamoxifen as first-line endocrine therapy in postmenopausal women with hormone receptor-positive advanced breast cancer

BackgroundFour randomised controlled trials (RCTs) in postmenopausal women with advanced breast cancer (ABC) comparing aromatase inhibitors (AIs) versus the selective estrogen receptor modulator tamoxifen, each individually reported significantly longer progression-free survival (PFS) but none showed a significant difference overall (OS). In these between 6.8% and 55% of tumours were hormone (HR) status unknown or negative. This meta-analysis restricted comparison to HR-positive (HR+) tumours.MethodsAnonymised individual patient data obtained from three RCTs, EORTC (exemestane tamoxifen), Study 0027 0030 (both anastrozole tamoxifen). For remaining RCT (Femara PO25; letrozole odds ratio (OR) hazard (HzR), confidence intervals clinical study report, for patients HR+ tumours, addition published data. total, 2296 patients; 1560 (68%) had ABC.FindingsThe OR benefit rate was 1.56, favour AIs (p < 0.001). The duration not increased by (HzR 0·88; p = 0.08). PFS HzR (0.82) 0·007). However, OS (1.05) different tamoxifen 0.42).InterpretationAlthough third generation put more into ‘clinical benefit’, their longer. Overall, while this resulted greater AIs, did translate improvement OS.