Breast Neoplasms/chemistry; Carcinoma, Ductal, Breast/chemistry; Carcinoma, Lobular/chemistry; ErbB Receptors/metabolism; Neoplasm Proteins/analysis; Receptor, ErbB-2/metabolism; Amphiregulin; Betacellulin; Breast Neoplasms/mortality; Breast Neoplasms/pathology; Carcinoma, Ductal, Breast/mortality; Carcinoma, Ductal, Breast/pathology; Carcinoma, Lobular/mortality; Carcinoma, Lobular/pathology; Disease-Free Survival; EGF Family of Proteins; Epidermal Growth Factor/analysis; Epiregulin; Female; Gene Expression Profiling; Glycoproteins/analysis; Heparin-binding EGF-like Growth Factor; Humans; Intercellular Signaling Peptides and Proteins/analysis; Intracellular Signaling Peptides and Proteins/analysis; Neoplasm Invasiveness; Neoplasm Proteins/genetics; Nerve Growth Factors/analysis; Nerve Tissue Proteins/analysis; Neuregulin-1; Neuregulins/analysis; Prognosis; RNA, Messenger/analysis; RNA, Neoplasm/analysis; Receptors, Estrogen/analysis; Transforming Growth Factor alpha/analysis