Breast nipple aspirate fluids (NAF) can be obtained non-invasively from women, making analyses of this fluid relevant to studies of breast cancer risk. The inter-individual variation for lipid oxidation products (a type of damage to fats) in NAF is more than 100-fold, and these oxidation products are likely to have a toxic effect on the breast epithelial cells. During breast ductal lavage, NAF is first aspirated, and the ducts producing fluid are then subjected to lavage to obtain epithelial cells. The nuclear features (morphology) of these cells can then be examined. Nuclear morphology is a quantitative method to observe subtle changes in nuclear features, and these measures in benign breast biopsies have been shown to have prognostic value for breast cancer risk.