Association between c-myc amplification and other biologic features and prognosis in primary breast cancer

673 Background: Amplification of c-myc is found in about 15% of breast cancers, half of which show HER2 coamplification. c-myc protein regulates cell proliferation, differentiation and apoptosis, but its prognostic impact remains controversial and varies on the basis of levels of cyclins and growth factors. Methods: c-myc amplification was retrospectively assessed in 67 consecutive HER2-amplified primary breast cancers (PBCs) and in 70 HER2-negative PBC controls using fluorescence in situ hybridization. We evaluated the correlation between c-myc and HER2 amplification, the association between c-myc amplification and pathological features such as estrogen receptors (ER), progesterone receptors (PgR), grade, tumor size, and lymph node metastasis, and the impact of c-myc and HER2 amplification on disease-free survival (DFS) and overall survival (OS). Correlations among qualitative variables were assessed using the chi-square test, while DFS and OS were estimated by the product-limit method and compared using...