Use of Subcutaneous and Intravenous Trastuzumab: Real-World Experience from Three Hospitals in Sweden

Aim: We aimed to describe the use of subcutaneous (sc.) trastuzumab use in a real-world setting. Patients & methods: This retrospective cohort study evaluated electronic medical records of patients with early breast cancer and trastuzumab use from January 2010 to February 2018 in three hospitals in Sweden. Results: In total, 363 patients received trastuzumab during study period. Of these, 217 (59.8%) patients started treatment with sc. trastuzumab and 146 (40.2%) with intravenous trastuzumab. After sc. trastuzumab approval, use of sc. trastuzumab increased from 70.2% in 2014 to 100% in 2017. Since 2013, 34 of 35 (97.4%) patients who started with intravenous trastuzumab switched to sc. formulation. Conclusion: Trastuzumab sc. quickly became the prevailing formulation for treatment in HER2-positive early breast cancer.