Tolaney SM, Guo H, Pernas S, et al. - In the Adjuvant Paclitaxel and Trastuzumab trial, a 3-year disease-free survival (DFS) of 98.7% was reported in patients treated for small human epidermal growth factor receptor 2 (HER2)–positive breast cancer, so researchers focused on longer-term outcomes and exploratory findings in this planned secondary analysis to describe the biology of small HER2-positive tumors and genetic factors that may predispose to paclitaxel-induced peripheral neuropathy. Paclitaxel (80 mg/m²) with trastuzumab for 12 weeks, followed by trastuzumab for 9 months was administered to patients with HER2-positive breast cancer with tumors 3 cm or smaller and negative nodes. From October 2007 to September 2010, 410 patients were enrolled. The 7-year DFS was 93% with four (1.0%) distant recurrences. The 7-year overall survival was 95%. Overall, excellent long-term outcomes folowing treatment with adjuvant paclitaxel and trastuzumab were revealed with longer follow-up. In small HER2-positive tumors, the distribution of PAM50 intrinsic subtypes was comparable to what was reported earlier for larger tumors.