Molecular subtyping using MammaPrint and BluePrint as an outcome predictor in U.S. breast cancer (BC) patients.

9 Background: Combined use of MammaPrint and a molecular subtyping profile (BluePrint) identifies disease subgroups with marked differences in long-term outcome and response to neo-adjuvant therapy (Gluck SABCS2011). The aim of this study was to evaluate the prognostic value of Molecular Subtyping using MammaPrint and BluePrint in women with early stage BC treated at U.S. institutions following National Comprehensive Cancer Network (NCCN) standard guidelines. Methods: Frozen tumor samples from 180 BC patients (TI-III, N0-Ib) median age 57 years at diagnosis (range 28-89) were suitable for hybridization on full genome array. MammaPrint and BluePrint Molecular Subtypes were determined and survival for Luminal A (MammaPrint Low Risk), Luminal B (MammaPrint High Risk), HER2-type and Basal-type patients was assessed. Patients were treated either with breast conserving therapy or mastectomy with axillary lymph node dissection between 1992 and 2005. The median follow-up is 12.7 years. 71% was ER positive and 20%...