Purpose: The benefits of adding ovarian suppression to either tamoxifen or aromatase inhibitors as adjuvant breast cancer therapy in premenopausal women are controversial. Therefore, we performed a systematic literature review and meta-analysis of relevant randomized trials.
Methods: We identified and combined four qualifying trials reporting disease-free survival (DFS) and overall survival (OS) using meta-analysis.
Results: Combining ABCSG-12, SOFT, and TEXT studies, there were 65 fewer DFS events (HR 0.89, 95% CI 0.57-1.39) but 30 more deaths for ovarian suppression plus aromatase inhibitor compared to ovarian suppression plus tamoxifen (HR 1.31, 95% CI 0.93-1.84, P = 0.12, τ = 0.03, heterogeneity, P = 0.18). DFS and OS were more concordant for combined SOFT and E-3193 findings; for ovarian suppression plus tamoxifen compared to tamoxifen alone, there were 24 fewer DFS events (HR 0.83, 95% CI 0.67-1.07, P = 0.09, τ 2 = 0) and 14 fewer deaths (HR 0.76, 95% CI 0.53-1.07). The SOFT Estrogen Substudy demonstrated inconsistent estrogen suppression with combined ovarian suppression and aromatase inhibitor.
Conclusion: Given the discordance between DFS and OS and inconsistent estrogen suppression with ovarian suppression plus aromatase inhibitor, adding aromatase inhibitor to ovarian suppression as adjuvant therapy in premenopausal women is premature.
Keywords: Aromatase inhibitor; Breast cancer; Gonadotropin-releasing hormone agonists; Ovarian suppression; Premenopausal; Tamoxifen.