PTEN Loss Is Associated with Worse Outcome in <i>HER2</i> -Amplified Breast Cancer Patients but Is Not Associated with Trastuzumab Resistance

This study is the largest to date examining PTEN status in breast cancer and the data suggest that the rate and significance of PTEN status differ between HER2-positive and HER2-negative disease. Furthermore, the data clearly suggest that HER2-positive patients with PTEN loss still benefit from trastuzumab.