Gene expression profile in node negative breast tumor

We analyzed gene expression profile in node negative breast tumor for molecular subtype classification Fresh frozen primary tumors were collected at the time of diagnosis from 92 patients with operable breast cancer previously untreated and undergoing radical or conservative surgery at the Istituto Nazionale Tumori of Milano (INTM) between1990 and 1998. All patients were pathologically defined as axillary node negative and were not submitted to any type of adjuvant systemic treatment until relapse.