Real-world clinical outcomes of patients with stage I HER2-positive breast cancer treated with adjuvant paclitaxel and trastuzumab.

Up to 20% of breast cancer overexpress HER2 protein, making it a reliable target for antibody-based treatments. In early HER2-positive breast cancer avoiding anthracycline-based chemotherapy is a challenge. Based on the single-arm phase II APT trial results, adjuvant paclitaxel/trastuzumab is an accepted regimen for patients with stage I HER2-positive disease. In our retrospective study of 240 patients, the median tumor size was 12.0 mm (IQR 9 -15), and 204 (85%) had estrogen receptor-positive disease. After a median follow-up of 4.6 years, 3-year real-world disease-free survival, distant DFS, and overall survival were 98.8% (95% confidence interval (CI), 96.2-99.6), 99.2% (95% CI, 96.7-99.8), and 98.3% (95% CI, 96.2-99.6), respectively. In a real-world setting, an adjuvant paclitaxel/trastuzumab regimen was associated with low recurrence rates among women with stage I, HER2-positive breast cancer. Additionally, we reviewed other treatment optimization strategies attempted or ongoing in HER2-positive breast cancer.