Non-lesion-directed minimally invasive breast tissue sampling is currently used in the research setting both for risk stratification and for acquisition of material for response biomarkers in phase II chemoprevention trials. Prospective data linking morphology to eventual development of cancer are currently available only for nipple aspirate fluid harvest (NAF) and random periareolar fine needle aspiration (RPFNA). The finding of atypia with either of these two techniques increases relative risk to a level at least as great as that which would be expected with atypical hyperplasia in a diagnostic biopsy (1, 2). Both techniques improve risk predictions based on the widely used Gail model. NAF has been shown to improve discriminatory accuracy for average risk (3), and RPFNA improves discriminatory accuracy for high-risk (4) cohorts. The main drawback for NAF is that f15% to 50% of women do not produce it and, even if produced, NAF generally contains few epithelial cells (1, 5). Although RPFNA produces an evaluable cytomorphology specimen in more than 90% of high-risk women (2), if severe atypia is encountered, the location of the abnormality is uncertain. It was hoped that ductal lavage would overcome the drawbacks of both the NAF and RPFNA procedures. Ductal lavage might provide more cells and evaluable cytomorphology more frequently than NAF. The ability to identify and recannulate specific ducts would theoretically give ductal lavage an advantage over RPFNA by reducing sampling variance in prevention trials as well as providing a means of identifying the site of very abnormal cells if and when they are encountered.At first, the future seemed bright for ductal lavage. Dooley et al. (5) in a multicenter study reported that 60% of high-risk women presenting for breast tissue -based risk assessment were able to produce NAF, successfully underwent duct cannulation, and had evaluable epithelial cells in their ductal lavage specimen. Further, the median number of cells from evaluable specimens was increased from 120 with NAF to 4,000 to 13,500 with ductal lavage (5). Other investigators reported similar results (6, 7). Investigators highly skilled in this technique have reported that even non -NAF-producing ducts could be cannulated, and epithelial cells harvested (8 -10); however, a lavage is more likely to yield adequate cells if women undergoing this procedure produce NAF and are premenopausal (11,12). Based on these preliminary studies, an industry-sponsored trial was initiated in which women undergo ductal lavage at intervals and are then followed for the development of breast cancer.A study by Khan et al. (9) markedly diminished hope that ductal lavage might be used as a reliable early detection tool because the sensitivity of lavage in breasts known to have cancer was only 13% to 42%, depending on whether mild or severe atypia was used as the indicator lesion. This seeming paradox may be explained by the fact that not all cancers are associated with fluid production, nor do they all originate in ducts that empt...