De-escalated Therapy Omitting Anthracyclines for Stage I HER2-positive Breast Cancer: A Retrospective Observational Study.

BACKGROUND It is unclear whether the de-escalated therapy that omits anthracycline-based chemotherapy is as beneficial as standard therapy for patients with stage I human epidermal growth factor receptor 2-positive (HER2+) early breast cancer. PATIENTS AND METHODS We retrospectively investigated 95 patients with pathological stage I HER2+ early breast cancer who underwent adjuvant treatment from April 2009 to December 2018. RESULTS We assessed 45 patients who underwent standard therapy containing anthracyclines, 35 patients who underwent paclitaxel plus trastuzumab (P+TRA group), and 15 patients who underwent trastuzumab monotherapy or no adjuvant therapy; the 5-year invasive disease-free survival rates were 97.8%, 92.9%, and 93.3%, respectively (p=0.255). Adverse events were significantly less frequent in the P+TRA group than that in the standard therapy group. CONCLUSION In a real-world setting, de-escalated therapy without anthracyclines demonstrated excellent outcomes similar to the standard therapy containing anthracyclines as well as lower adverse events.