Effect of chemotherapy and trastuzumab as adjuvant treatment for small HER2-positive breast cancer: A single-institution experience.

e11031 Background: The addition of trastuzumab as adjuvant treatment has allowed 50% reduction for relapse in >1cm size tumor, early-stage HER2-positive breast cancer (BC). However, it is not clear if this benefit is present as well in smaller, node-negative (N0) tumors. We retrospectively reviewed our experience in a single institution. Methods: From 1997 to 2007, BC patients (pts) with HER2-positive, T1a-b N0, early BC were included. Epidemiologic, clinical and characteristic tumor data were collected from patients at 12 de Octubre University Hospital (Madrid) Results: 35 pts with a median age of 55 years (range 35-82) were included. Six pts (17%) had T1a (≤ 0,5 cm) tumors and 29 (83%) T1b (0,5-1 cm). All cases had no lymph node involvement, tested by lymphadenectomy (30 pts, 86%) or sentinel-node biopsy (5 pts, 14%). Eighteen pts (51%) underwent mastectomy and 17 pts (49%) conservative surgery. Most frequent histology was infiltrating ductal carcinoma (31pts, 89 %). HER2 testing was performed by IHC in...