Memorial Sloan-Kettering Cancer Center physician-scientists report that women with small, node-negative, HER2-positive breast cancer may obtain a significant benefit from adjuvant chemotherapy with trastuzumab (Herceptin®), a drug previously shown to improve outcomes in advanced cancer and prevent the return of cancer in women diagnosed with higher-risk, early-stage, HER2-positive breast cancer. This study appears online in the journal Cancer, and will be published in a future print edition.