 OUTLINE: Patients and participants undergo nipple secretion and blood sample collection at baseline and at 1 month for evaluation of levels of carcinoembryonic antigen CEA and patterns of protein expression that may indicate the presence of early-stage breast cancer. Nipple secretions are obtained from both the affected and unaffected breasts via capillary, aspiration nipple aspirate fluid NAF, and nipple blot . CEA levels are measured in serum samples, NAF, and other nipple secretions using standard CEA protein assays. Nipple secretions obtained by nipple blot are analyzed by nipple blot assay to determine the feasibility of using this technique. The results of the nipple blot assay are then compared with the results of standard protein assays to evaluate the sensitivity and specificity of the nipple blot test. CEA expression is also determined in breast tissue specimens obtained from patients undergoing diagnostic biopsy. Specimens are examined by IHC for tissue CEA levels. Proteomic profiles in NAF and serum samples are measured using liquid chromatography mass spectrometry and then compared with proteomic profiles in normal healthy controls. 