Abstract
The ductal approach to breast cancer, encompassing nipple aspiration, ductal lavage and duct endoscopy, allows assessment of breast ductal epithelial cells and their local microenvironment in a graded process of increasing invasiveness. Samples of ductal epithelial cells sufficient for cytological diagnosis may be safely collected, titres of individual proteins showing variation with breast cancer status may be measured, and abnormal pathology within the breast ducts may be directly visualized. Identification of surrogate molecular markers may facilitate early breast cancer detection, in conjunction with cytological assessment, and be useful for individual prediction of breast cancer risk and assessment of treatment response. However, the sensitivity and specificity of the ductal approach require further evaluation. The small quantities of nipple aspiration fluid available for analysis, and difficulties identifying and cannulating ducts remain important limitations of these techniques.