6 versus 12\u200amonths of adjuvant trastuzumab in HER2+ early breast cancer

Abstract

Abstract Background: Adjuvant trastuzumab improves survival outcomes of human epidermal receptor 2 positive early breast cancer patients. Currently, administration of 12\u200amonths adjuvant trastuzumab is the standard therapy. However, whether 6\u200amonths treatment is non-inferior to the standard 12\u200amonths treatment remains controversial. Methods: Relevant records were searched in PubMed, Cochrane Library, Web of Science, and EMBASE through Jan 14, 2020. Pooled hazard ratios (HRs) and 95% confidence intervals (CIs) for disease-free survival (DFS) and overall survival (OS) were meta-analyzed. The primary endpoint was DFS with a non-inferiority hazard margin of 1.2 and the second was OS with 1.43. Results: Three randomized clinical studies met the inclusion criteria, including 3974 patients in 6\u200amonths group and 3976 in 12\u200amonths group. HR for DFS was 1.18 (95% CI 0.97–1.44, P\u200a=\u200a.09), with the non-inferiority margin comprised in the 95% CI. HR for OS was 1.14 (95% CI 0.98–1.32, P=\u200a.08), whereas the upper limit of 95% CI did not exceed the non-inferiority hazard margin. Conclusion: Our analysis failed to show that 6\u200amonths treatment was non-inferior to 12\u200amonths treatment in improving the DFS. Although the non-inferiority of the 6-month adjuvant trastuzumab treatment was found for OS, considering that breast cancer patients should receive additional systematic therapies when disease progression or relapse happens, we suggest that 12\u200amonths adjuvant trastuzumab treatment should remain the standard therapeutic strategy for patients with early human epidermal receptor 2 positive breast cancer.